Exosuit system

ABSTRACT

A flexible exosuit includes rigid and flexible elements configured to couple forces to a body of a wearer. Further, the flexible exosuit includes flexible linear actuators and clutched compliance elements to apply and/or modulate forces and/or compliances between segments of the body of the wearer. The flexible exosuit further includes electronic controllers, power sources and sensors. The flexible exosuit can be configured to apply forces to the body of the wearer to enable a variety of applications. In some examples, the flexible exosuit can be configured to augment the physical strength or endurance of the wearer. In some examples, the flexible exosuit can be configured to train the wearer to perform certain physical tasks. In some examples, the flexible exosuit can be configured to record physical activities of the wearer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and incorporates by reference thecontent of U.S. Provisional Application No. 61/790,406, filed Mar. 15,2013, U.S. Provisional Application No. 61/789,872, filed Mar. 15, 2013,U.S. Provisional Application No. 61/917,820, filed Dec. 18, 2013, andU.S. Provisional Application No. 61/917,829, filed Dec. 18, 2013.

GOVERNMENT ACKNOWLEDGEMENT

This invention was made in part with Government support under contractW911QX-12-C-0049 awarded by the United States Army. The Government hascertain rights in this invention.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

Many physical activities require a participant in the activity toperform to the limit of their physical ability, testing theparticipant's endurance, strength, coordination, shock tolerance, orother physical variables. Warfighters can be expected to carry heavyloads across long distances, taxing their endurance and risking injurydue to falls, unstable terrain, or other unanticipated physical shocks.The elderly or the physically disabled can experience difficulty inperforming activities of daily living, due to reduced endurance,strength, injury-resistance, balance, or other issues. Movers or otherpersons engaged in physical labor can be at increased risk of injury dueto repeatedly lifting heavy loads over long durations and difficultycoordinating physical efforts (e.g., lifting a large object) betweenmultiple people. Athletes can be exposed to joint, tendon, or otherforces sufficient to cause significant temporary or permanent injury.Individuals recovering from surgery or a disabling injury may be unableto perform the minimum tasks necessary to begin rehabilitation, and thusmay be barred from recovery. Other examples exist of populations andactivities that respectively may require more physical ability than isavailable to members of the population or to participants in theactivities.

Assistive devices may be able to alleviate some of these issues. Avariety of assistive devices, including various exoskeleton-baseddevices, have been developed to increase a user's strength, fatigueresistance, coordination, or other factors. These exoskeletons or otherdevices can be powered or unpowered, and may be controlled by feedbackfrom the user's movements, be operated in a feed-forward manner, or becompletely passive (e.g., hernia belts, lifting harnesses). Assistivedevices can include electrical or mechanical actuators, sensors, andcontrollers. Various assistive devices have been applied to some of theabove populations and activities with varying degrees of success.

SUMMARY

Some embodiments of the present disclosure provide a programmable bodyaugmentation system that includes (i) a flexible suit configured to beworn over at least a portion of a human body; (ii) one or more flexiblelinear actuators coupled to the flexible suit, wherein the one or moreflexible linear actuators are operable to apply forces between segmentsof the human body such that the forces applied by the one or moreflexible linear actuators augment forces applied by musculature in thehuman body; (iii) one or more clutched-compliance elements coupled tothe flexible suit, wherein the one or more clutched-compliance elementsare operable to provide controllable levels of compliance betweensegments of the human body; and (iv) a controller disposed in theflexible suit, wherein the controller is configured to executecomputer-readable programs to operate the one or more flexible linearactuators to apply forces between segments of the human body and tooperate the clutched-compliance elements to provide controlled levels ofcompliance between segments of the human body in a plurality ofdifferent ways to provide a plurality of different modes of operation.

Some embodiments of the present disclosure provide a method thatincludes: (i) coupling a programmable body augmentation system to ahuman body, wherein the programmable body augmentation system includes:(a) one or more flexible linear actuators, wherein the one or moreflexible linear actuators are operable to apply forces between segmentsof the human body such that the forces applied by the one or moreflexible linear actuators augment forces applied by musculature in thehuman body; (b) one or more clutched-compliance elements, wherein theone or more clutched-compliance elements are operable to providecontrollable levels of compliance between segments of the human body;and (c) a controller, wherein the controller is configured to executecomputer-readable programs to operate the one or more flexible linearactuators to apply forces between segments of the human body and tooperate the clutched-compliance elements to provide controlled levels ofcompliance between segments of the human body in a plurality ofdifferent ways to provide a plurality of different modes of operation;(ii) selecting one of the modes of operation; (iii) performing one ormore actions of the human body related to the selected mode of operationwhile the controller operates the one or more flexible linear actuatorsto apply forces to the human body and operate the one or moreclutched-compliance elements to provide levels of compliance betweensegments of the human body related to the one or more actions.

Some embodiments of the present disclosure provide a method thatincludes: (i) providing a programmable body augmentation system, whereinthe programmable body augmentation system comprises: (a) a flexible suitconfigured to worn over at least a portion of a human body; (b) aplurality of body-augmentation elements coupled to the flexible suit ina particular physical arrangement, the body-augmentation elementsincluding one or more flexible linear actuators and one or moreclutched-compliance elements, wherein the one or moreclutched-compliance elements are operable to provide controllable levelsof compliance between segments of the human body, and wherein the one ormore clutched-compliance elements are operable to provide controllablelevels of compliance between segments of the human body; and (c) acontroller disposed in the flexible suit, wherein the controller can beprogrammed to control the forces applied by the one or more flexiblelinear actuators and the compliance provided by the clutched-complianceelements; (ii) enabling a first mode of operation of the programmablebody augmentation system, wherein the first mode of operation involvesthe one or more flexible linear actuators applying forces and the one ormore clutched-compliance elements providing compliances related to afirst type of action of the human body, and wherein enabling the firstmode of operation of the programmable body augmentation system comprisesprogramming the controller based on the first mode of operation withoutchanging the particular physical arrangement of body-augmentationelements; and (iii) enabling a second mode of operation of theprogrammable body augmentation system, wherein the second mode ofoperation involves the one or more flexible linear actuators applyingforces and the one or more clutched-compliance elements providingcompliances related to a second type of action of the human body,wherein the second type of action is different than the first type ofmovement, and wherein enabling the second mode of operation of theprogrammable body augmentation system comprises programming thecontroller based on the second mode of operation without changing theparticular physical arrangement of body-augmentation elements.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a flexible exosuit.

FIG. 1B illustrates in detail a section of the flexible exosuit of FIG.1A.

FIG. 2A illustrates elements of an exotendon.

FIG. 2B illustrates elements of an exotendon.

FIG. 2C illustrates elements of an exotendon.

FIG. 2D is a side view of an exotendon.

FIG. 2E is a front view of the exotendon of FIG. 2D.

FIG. 3A is a schematic view of an exotendon wrapped partially around acapstan.

FIG. 3B is a schematic view of a cable coupled to an exotendon andwrapped around a capstan.

FIG. 4A illustrates a twisted string actuator.

FIG. 4B is a close-up, cutaway view of elements of the twisted stringactuator illustrated in FIG. 4A.

FIG. 5A illustrates a twisted string actuator.

FIG. 5B illustrates a twisted string actuator.

FIG. 5C illustrates a twisted string actuator.

FIG. 5D illustrates a twisted string actuator.

FIG. 5E illustrates a twisted string actuator.

FIG. 5F illustrates a twisted string actuator.

FIG. 5G illustrates a twisted string actuator.

FIG. 6A illustrates a twisted string actuator.

FIG. 6B illustrates a twisted string actuator.

FIG. 6C illustrates a twisted string actuator.

FIG. 6D illustrates a twisted string actuator.

FIG. 6E illustrates a twisted string actuator.

FIG. 6F illustrates a twisted string actuator.

FIG. 7A illustrates a nested twisted string.

FIG. 7B illustrates the nested twisted string of FIG. 7A, twisted.

FIG. 7C shows a top view of the nested twisted string of FIG. 7A.

FIG. 8A is a schematic cross-sectional view of an electroadhesiveelement.

FIG. 8B is a front view of the electroadhesive element illustrated inFIG. 8A.

FIG. 8C is a front view of part of an electroadhesive element.

FIG. 9 is a functional block diagram of an example flexible exosuit.

FIG. 10A is a schematic diagram of a smart tendon exomuscle.

FIG. 10B is a schematic diagram of a smart tendon exomuscle.

FIG. 10C is a schematic diagram of a smart tendon exomuscle.

FIG. 10D is a schematic diagram of a smart tendon exomuscle.

FIG. 11A is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11B is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11C is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11D is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11E is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11F is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11G is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11H is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 11I is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 12A is a side view of elements of a flexible exosuit being worn bya wearer.

FIG. 12B is a back view of the flexible exosuit illustrated in FIG. 12A.

FIG. 13A is a schematic illustrating a model of a leg.

FIG. 13B is a schematic illustrating a model of a leg.

FIG. 14 illustrates patterns of operation of elements of the model of aleg illustrated in FIG. 13A.

FIG. 15A illustrates controllers that could be used to operate elementsof the model of a leg illustrated in FIG. 13A.

FIG. 15B illustrates recorded natural patterns of operation of a humanleg and patterns of operation of elements of the model of a legillustrated in FIG. 13A and state transitions of the controllersillustrated in FIG. 15A.

FIG. 16A shows a side view of a schematic of a flexible exosuit worn ona leg of a wearer.

FIG. 16B shows a front view of elements of the flexible exosuitillustrated in FIG. 16A.

FIG. 16C shows a back view of elements of the flexible exosuitillustrated in FIG. 16A.

FIG. 17 shows a schematic of a flexible exosuit worn on an arm of awearer.

FIG. 18 illustrates a flexible exosuit and system configured tocommunicate with the flexible exosuit.

FIG. 19 illustrates a schematic of a control scheme for a flexibleexosuit.

FIG. 20A illustrates an example process for operating a flexibleexosuit.

FIG. 20B illustrates an example process for operating a flexibleexosuit.

FIG. 21A is an example of a user interface for a flexible exosuit.

FIG. 21B is an example of a user interface for a flexible exosuit.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying figures, which form a part hereof. In the figures, similarsymbols typically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, figures, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the scope of the subject matter presented herein. It willbe readily understood that the aspects of the present disclosure, asgenerally described herein, and illustrated in the figures, can bearranged, substituted, combined, separated, and designed in a widevariety of different configurations, all of which are explicitlycontemplated herein.

I. Overview

Some embodiments of the present disclosure provide a flexible exosuit(alternatively referred to as an exosuit, a WarriorWeb, a strength suit,and/or a programmable body augmentation system) configured to be worn bya wearer and to apply forces to the wearer, among other functions, toenable various physical activities of the wearer. In some examples, thiscould include providing forces between segments of the body of thewearer to augment forces applied by the musculature of the wearer'sbody. Some embodiments of the present disclosure provide variouselements that could be incorporated into such an exosuit to enablefunctions of the exosuit. Some embodiments of the present disclosureprovide applications and modes of operation of such an exosuit.

FIGS. 1A and 1B illustrate a flexible exosuit 100 being worn by a wearer110. FIG. 1A additionally illustrates loads 120 a and 120 b beingrespectively carried in the arms of and worn on the back of the wearer110. Flexible exosuit 100 is configured to apply forces to the wearer110, elements of the flexible exosuit 100, and/or one or both of theloads 120 a, 120 b to facilitate one or more activities of the wearer110. For example, flexible exosuit 100 could be operated to assist thewearer 110 in walking by adding energy to the motion of the wearer's 110legs and/or by selectively extracting energy from the wearer's 110 legsduring one phase of locomotion and injecting a portion of the extractedenergy to assist the motion of the wearer's 110 legs during anotherphase of activity. In another example, the flexible exosuit 100 couldadditionally or alternatively enable the wearer 110 to carry loads 120a, 120 b heavier than the wearer 110 would be capable of carrying on hisown and/or carrying loads 120 a/120 b farther than the wearer 110 wouldbe capable on his own. Other activities of the wearer 110 could befacilitated by the flexible exosuit 100. Additionally or alternatively,the flexible exosuit 100 could be configured and/or operated to performother functions.

The flexible exosuit 100 includes a multitude of elements to enable thefunctions described herein. The flexible exosuit includes flexibleforce-transmitting elements (FFTEs) 130 configured to transmit forcesbetween elements of the flexible exosuit 100 and between elements of theflexible exosuit 100 and tissues of the wearer 110. The flexible exosuit100 additionally includes rigid force-transmitting elements (RFTEs) 140a, 140 b, 140 c configured to transmit forces between elements of theflexible exosuit 100 and between elements of the flexible exosuit 100and tissues of the wearer 110. In some examples, the RFTEs can becomposed of flexible elements and can be configured to be functionallyrigid when attached to other elements and/or the body of a wearer. SuchRFTEs could be considered conditionally rigid, in that their rigidtransmission of compressive or other forces is conditional upon theirbeing attached to the other elements and/or the body of a wearer.Conditionally rigid RFTEs could be configured to transmit forces (giventhe constraints above) similar to forces transmitted by a correspondingnon-conditionally rigid force-transmitting elements while being lighter,thinner, or otherwise superior according to some application than thecorresponding non-conditionally rigid force-transmitting elements.Mechanical forces are transduced by actuators of the flexible exosuit100, including twisted string actuators 150 a, 150 b, 150 c driven byelectrical motors 160 and exotendons 170 a, 170 b, 170 c, 170 d.Actuators (including 150 a-c, 170 a-d) can generate, absorb, store, orotherwise modulate forces between force-transmitting elements 130, 140a-c in order to generate, store, or otherwise modulate forces on orwithin the wearer 110 (e.g., joint torques about one or more joints ofthe wearer 110) to facilitate or enable functions of the flexibleexosuit 100 as described herein. The flexible exosuit 100 can includeadditional elements, including batteries, controllers, sensors, userinterfaces, communications devices, or other components according to anapplication.

Twisted string actuators (e.g., 150 a, 150 b, 150 c) are flexiblestructures capable of generating forces along their length. A twistedstring actuator includes at least two flexible ‘strands’ (e.g., wires,cables, ropes, fibers) twisted about each other (in cases where thereare two strings, the two strings can be referred to as a “twistedpair”). In some examples, a first end of a twisted string is attached toa first actuated element, and a second end of the twisted string,opposite the first end, is attached to a second actuated element suchthat the location of the second end does not translate relative to thesecond actuated element and such that the second end can be rotated by arotational actuator, e.g., an electric motor 160. The twisted stringactuator transduces a rotation or torque applied to the second end ofthe twisted string into a displacement or force, respectively, betweenthe first and second actuated elements. Properties of a twisted string(e.g., compliance, twist pitch, diameter, length) and the drivingrotational actuator (e.g., acceleration, speed, torque, rotationalinertia) can be chosen to produce a twisted string actuator having oneor more properties according to an application, for example, a high rateof change of displacement, a high transmission ratio between therotational actuator and the forces applied between the first and secondactuated elements, a certain compliance, or other properties. Further, atwisted string can be flexible and can be implemented in a curvedconfiguration. For example, the twisted string could be housed in astiff tube (similar to a Bowden cable, where the twisted string and thestiff tube are analogous to the inner cable and the outer housing,respectively) wrapped around a joint of the wearer 110, with each end ofthe twisted string attached as described above to a respective actuatedelement on either side of the joint. Such a twisted string actuatorcould be operated to apply forces between the first and second actuatedelements across the joint; further, the flexibility of the twistedstring and the stiff tube can allow the twisted string actuator toremain proximate to a surface of the wearer 110 as the joint moves or asother aspects of the flexible exosuit 100 or wearer 110 changeconfiguration. Note that a twisted string actuator can have more thantwo flexible strings, be connected to actuated elements in differentways, be driven by other or multiple rotational actuators, or beconfigured differently to these examples in other ways.

Exotendons (e.g., 170 a, 170 b, 170 c, 170 d) are structures capable oftransmitting forces along their length and capable of having one or moremechanical properties (e.g., a compliance) controlled by an electricalor other signal. Exotendons can be flexible or rigid. Exotendons can bethin, flexible, and conformal to a curved or flat surface. For example,an exotendon could include an electrostatic clutch (or some other typeof mechanical clutch) connected in series with a component having aspecified compliance (e.g., a spring). The clutch itself could have afirst compliance when inactive (possibly a very high compliance,corresponding to an effectively nearly complete mechanical decouplingbetween the ends of the clutch) and a second compliance when active(possibly a very low compliance, corresponding to the compliance ofindividual components of the clutch due to an effectively non-compliantmechanical coupling between the ends of the clutch). Thus, exotendonscould be considered a type of clutched-compliance element. The clutchand specified-compliance component could be discrete, or could beinterdigitated, intercalated, or otherwise assembled proximately to forman exotendon. Further, an exotendon could contain multiplespecified-compliance elements, independently or commonly-controlledclutches, or other elements. In some examples, the overall compliance ofan exotendon could be controlled to a variety of discrete or continuouslevels by controlling multiple clutches. In some examples, an exotendoncould be operated to store a mechanical energy, e.g. by engaging aclutch to prevent relaxation of a stretched specified-complianceelement, and to later release the stored mechanical energy. Otherconfigurations and methods of operating an exotendon are describedherein.

The flexible exosuit 100 could include additional wholly or partiallyflexible linear actuators (i.e., actuators capable of being operated toproduce a linear force and/or displacement and that are wholly orpartially flexible) and/or other varieties of wholly or partiallyflexible actuators. In some examples, the flexible exosuit 100 couldinclude actuators that include electroactive polymer artificial muscle(EPAM). EPAM actuators change size or shape in response to an appliedelectrical field. Conversely, a size or shape change in an EPAM actuatorcaused by an external force can cause an electric field to develop in oron the EPAM actuator. An EPAM actuator can include two or moreelectrodes configured to interact (by way of an electric field) with anelectroactive polymer material. The electroactive polymer material couldinclude dielectric, ferroelectric, electrostrictive, or otherelectrically-active molecules, crystals, or materials embedded in apolymer such that application of an electric field causes theelectrically-active materials to orient, expand, contract, or otherwiserespond to the electric field to cause the electroactive material tochange a size or shape. For example, the electroactive polymer materialcould be composed of an elastic dielectric configured to experienceelectrostatic compression. The electroactive material and electrodes canbe configured in a variety of ways to enable a desired relationshipbetween mechanical deformation of the EPAM and an electric field betweenthe electrodes. In some examples, the material and electrodes could beconfigured such that the EPAM actuator transduced an electric field intoa size change in one direction, such that the EPAM actuator could beoperated as a flexible linear actuator. EPAM actuators couldadditionally or alternatively be used to generate electrical energy frommechanical energy. In some examples, the flexible exosuit 100 couldinclude actuators that drive and/or apply a tension to a cable orcables. For example, the flexible exosuit could include a linear pullsolenoid attached to a cable. The linear pull solenoid could be attachedto a first actuated element and the end of the cable opposite the end ofthe cable attached to the solenoid could be attached to a secondactuated element. Application of an electrical current to the solenoidcould result in a force applied between and/or a displacement of thefirst and second actuated elements. Other wholly or partially flexibleactuators of the flexible exosuit are anticipated.

The flexible exosuit 100 could include composite actuators; that is,wholly or partially flexible assemblies mechanically connected between afirst actuated element and a second actuated element and including atleast one actuator. For example, the flexible exosuit 100 could includea smart tendon exomuscle (STEM) actuator that includes a linear actuatorand at least one clutched compliance element (that is, an element thatincludes a mechanical clutch mechanically coupled in series with acomponent having a specified compliance). The linear actuator could be atwisted string actuator. The clutched compliance element could beconfigured similarly to an exotendon as described herein. A STEM couldinclude a single twisted string actuator connected to the first actuatedelement and mechanically coupled in series with an exotendon connectedto the second actuated element. A STEM could include an exotendonconnected between the first and second actuated elements and connectedin parallel with a single twisted string actuator connected to the firstactuated element and mechanically coupled in series with an exotendonconnected to the second actuated element. A STEM could include a singletwisted string actuator connected to the first actuated element andmechanically coupled in series with an exotendon also connected to thefirst actuated element. A STEM could be configured to have a topologyand/or properties inspired by biological actuators, e.g., muscles andtendons, and could further be operated to mimic the operation ofbiological actuators. Other configurations of a STEM are anticipated. ASTEM could be operated to extract, store, inject, or otherwise transducemechanical forces and energies to and from a wearer 110 of the flexibleexosuit 100 and/or between elements of the flexible exosuit 100.

Forces could be transmitted between elements of the flexible exosuit 100and tissues of the wearer 110 through flexible elements in contact withthe skin of the wearer 110 and/or in contact with a form-fitting fabricor garment that is contact with the skin of the wearer 110. For example,actuators of the flexible exosuit 100 could transmit forces intoflexible force-transmitting elements (FFTEs) 130 that could, in turntransmit forces into the skin of the wearer 110. The forces transmittedinto the skin of the wearer may be compressive forces, shear forces, orother types and combinations of forces as described further below.Multiple FFTEs 130 could be flexibly or rigidly connected to each otherand to actuators to enable forces to be transferred to into the skin ofthe wearer according to a constraint or application. For example,multiple FFTEs 130 could be woven together and connected to an actuatorin such a way that the transmission of shear force from the actuatorand/or normal force between the multiple FFTEs 130 and the skin wasevenly spread across an area the wearer's skin. This constraint could beused to specify the configuration of the multiple FFTEs 130 according toa model of the anatomy of the wearer 110 or of some stereotypical and/orstatistically-derived wearer. Individual FFTEs 130 of the multiple wovenFFTEs 130 could wind helically around part of the anatomy of the wearer110 (e.g., a shank of a leg) such that the pitch of the helix decreasedwith distance from the point of attachment to the actuator. MultipleFFTEs 130 could additionally be configured to allow for attachment ofmultiple actuators and/or to allow transmission of forces from multipledirections. More than one set of multiple FFTEs 130 connected torespective more than one actuators could transmit forces into the samearea of skin of the wearer 110, for example, by being configured toslide over each other otherwise not significantly transmit forcesbetween each other while transmitted forces into the skin.

Forces could be transmitted between elements of the flexible exosuit 100and the wearer 110 through additional methods. FFTEs 130 and/or rigidforce-transmitting elements (RFTEs) 140 a, 140 b, 140 c could beconfigured to transmit forces into and/or adhere to skin in regions ofminimal skin strain, that is, regions of skin that experience relativelylittle strain during specified activities of the wearer 110 (e.g.,walking, running, jumping, lifting). Additionally or alternatively,FFTEs 130 could be configured to transmit forces into and/or adhere toskin along lines of non-extension of the skin, that is, lines of theskin that experience strain perpendicular to the lines but substantiallyno strain parallel to the lines during specified activities of thewearer 110. FFTEs 130 and/or RFTEs 140 a, 140 b, 140 c could beconfigured to transmit substantially no shear forces into skin,according to an application, by having beads, cylinders, or otherfreely-rotating elements coupled to the FFTEs 130 and/or RFTEs 140 a,140 b, 140 c such that a normal force is transmitted through one or morebeads, cylinders, or other freely-rotating elements and a shear forceresult in rotation of the one or more beads, cylinders, or otherfreely-rotating elements and displacement of the FFTE 130 and/or RFTE140 a, 140 b, 140 c. Other methods of transmitting force betweenelements of the flexible exosuit 100 and the wearer, including straps,boots, armor segments, and electroadhesive pads are anticipated.

The flexible exosuit 100 could include rigid elements, including RFTEs140 a, 140 b, and 140 c. RFTE 140 a is a rigid element configured tocouple forces to the foot of the wearer 110 by operating as or inconjunction with a boot. Some or all of the forces generated and/ortransmitted by twisted string actuator 150 a and exotendon 170 a aretransmitted into RTFE 140 a. RTFE 140 a could additionally include otherelement; for example, RTFE 140 a could include one or more EPAMactuators that could be operated to, for example, absorb and/or transmitenergy to the foot of the wearer 110 to increase the efficiency or someother factor of an activity (e.g., locomotion) of the wearer. RFTE 140 bis a rigid element configured to couple some or all of the forcesgenerated and/or transmitted by twisted string actuator 150 a andexotendon 170 a to other elements (e.g., FFTEs 130) of the flexibleexosuit 100 and/or skin of the wearer proximate to RFTE 140 b. RFTE 140c is a rigid element configured to couple forces from other elements ofthe flexible exosuit 100 to the torso of the wearer 110. Some or all ofthe forces generated and/or transmitted by twisted string actuators 150b, 150 c and exotendons 170 b, 170 c, 170 d are transmitted into RTFE140 c. RTFE 140 c can additionally transmit forces to/from FFTEs 130.RTFE 140 c is additionally configured to mount the load 120 b to allowforces from the load (e.g., force due to gravity) to be transmitteddirectly into the flexible exosuit 100, such that some or all of theforces necessary to transport the load 120 b are borne by the flexibleexosuit 100 instead of elements of the wearer's 110 back. Other RTFEsthan those illustrated in FIG. 1B could be included in the flexibleexosuit 100 and could be configured to transfer forces to the wearer 110and/or between other elements of the flexible exosuit 100 according toan application.

The flexible exosuit 100 could additionally include an undersuitconfigured to maintain the location of elements of the flexible exosuit100 relative to elements of the body of the wearer 110. The undersuitcould be composed of a variety of flexible fabrics, textiles, or othermaterials and could enable a variety of functions of the flexibleexosuit 100. For example, the undersuit could include Kevlar to protectthe wearer 100 from projectiles, Gore-Tex to manage moisture emitted bythe skin of the wearer 110, or other materials. The undersuit, RTFEs(e.g., 140 a, 140 b, 140 c), FFTEs (e.g., 130), and/or othernon-electronically-operable elements of the flexible exosuit 100 couldbe referred to as a flexible suit. The coupling ofelectronically-operable elements (e.g., exotendons 170 a, 170 b, 170 c,170 d, twisted string actuators 150 a, 150 b, 150 c, or other actuatorsor other elements disposed on or within the flexible exosuit 100) to theflexible suit could enable the operation of the electronically-operableelements to apply forces, torques and/or compliances to the body of thewearer 110.

The flexible exosuit 100 includes additional elements. The flexibleexosuit 100 includes one or more controllers configured to operate theflexible exosuit 100. The controller(s) could be configured to receivedata from a plurality of sensors in the flexible exosuit 100, generatecommands to operate actuators (e.g., 150 a-c, 170 a-d) of the flexibleexosuit 100, and to perform other functions. The controller(s) could beconfigured to operate communications elements in the flexible exosuit100, for example, Bluetooth radios, WiFi radios, LTE or other cellularradios, near-field RF communications devices, modems, or othercommunications devices. The controller(s) could be configured to operatesuch communications devices to receive commands, send telemetry, enablecommunications between the wearer 110 and some other person or system,or enable some other function. The controller(s) could be configured tooperate one or more user interfaces (UIs) in the flexible exosuit 100and/or in systems in communication with the flexible exosuit 100. Forexample, the controller(s) could operate a touch screen disposed on orin a sleeve worn by the wearer 110 to present information about theoperation of the flexible exosuit 100 to the wearer and/or to receivecommands from the wearer 110, e.g., commands to alter the functioning ofthe flexible exosuit 100. UIs in the flexible exosuit 100 could includedisplays, touchscreens, touchpads, buttons, sliders, knobs, indicatorlights, speakers, headphones, microphone, or other elements.

The controller(s) could additionally or alternatively be configured tosend and/or receive commands from the wearer 110 using sensors and/oractuators of the flexible exosuit 110. In some examples, thecontroller(s) could be configured to use sensors disposed in theflexible exosuit 100 to detect command gestures performed by the wearer110 and to alter the functioning of the flexible exosuit 100 based onthose command gestures. In some examples, the controller(s) could useactuators or other elements of the flexible exosuit 100 to providefeedback to the wearer 110, to indicate a state of the flexible exosuit100 to the wearer, and/or to provide some other information to thewearer 110. For example, the controller(s) could produce a pulse orsequence of pulses using twisted string actuator 150 c to indicate thatthe wearer 110 should adopt a more crouched posture. In another example,the flexible exosuit 100 could include one or more vibrating, heating,or electrostimulating elements, and the controller(s) could operate thevibrating, heating, or electrostimulating elements to indicate a stateof the flexible exosuit 100 to the wearer, and/or to provide some otherinformation to the wearer 110. Other methods of using elements of theflexible exosuit 100 to indicate information to the wearer 110 areanticipated.

The flexible exosuit 100 includes a plurality of sensors configured todetect information about the operation and status of the flexibleexosuit 100, the wearer 110, and/or an environment of the wearer. Thesesensors include but are not limited to force sensors (e.g., load cells),strain or displacement sensors (e.g., capacitive sensors, laser orultrasonic rangefinders, linear encoders, rotary encoders on rotaryelements of rotary-to-linear transducers or transmissions), anglesensors (e.g., magnets and magnetometers, filtered accelerometers,magnetometers, and/or gyroscopes), location, velocity, and/oracceleration sensors (e.g., GPS receivers, filtered or unfilteredaccelerometers, magnetometers, and/or gyroscopes), temperature sensors,EMG sensors, ECG sensors, pulse sensors, blood pressure sensors,galvanic skin response sensors, humidity sensors, chemical sensors(e.g., CO₂, CO, O₂ sensors), ionizing radiation sensors, cameras, SONAR,LIDAR, proximity sensors, or other sensors. The sensors can be discreteor the sensors can be part of an actuator or other element of theflexible exosuit 100. For example, an exotendon could be configured tobe used to detect one or more properties of the exotendon or theenvironment of the exotendon (e.g., to detect a strain and/or forceexperienced by the exotendon by measuring an impedance or voltagebetween and/or current through a pair of electrodes of the exotendon).

The sensors can be operated to generate data that can be used to operatethe flexible exosuit 100. Data generated by the sensors could be used bya controller included in the flexible exosuit 100 to operate actuators(e.g., e.g., 150 a-c, 170 a-d) to perform some function. For example,the sensors could generate data indicating that the wearer 110 wasengaging in locomotion and that the wearer 110 was at a first specifiedphase of a stereotypical locomotor cycle, and the controller could usethat data to operate the exotendons 170 a-d to extract negative workfrom the wearer 110. At a later point in time, the sensors couldgenerate data indicating that the wearer 110 was engaging in locomotionand that the wearer 110 was at a second specified phase of thestereotypical locomotor cycle, and the controller could use that data tooperate the exotendons 170 a-d to assist the locomotion of the wearer110 by transferring energy to the leg of the wearer 110 and/or tooperate the twisted string actuators 150 a, 150 b, 150 c to transferenergy to the leg of the wearer 110.

Flexible exosuits could additionally include elements corresponding toan arm or other additional or alternate anatomy of a wearer other thanthe leg (as illustrated by the flexible exosuit 100 of FIGS. 1A and 1B).Such flexible exosuits could be configured to increase the upper-bodystrength of a wearer and/or to assist in the carrying of loads in thearms of a wearer. A flexible exosuit having elements corresponding to anarm of a wearer could be configured to transfer mechanical energyto/from the arms of a wearer from/to the legs of the wearer, forexample, to enable locomotion across a farther distance than the usercould achieve without the transfer of mechanical energy from the arms tothe legs of the wearer. A flexible exosuit could be configured to besymmetric across the midline of wearer (i.e., elements disposed relativeto the left leg of a wearer are duplicated and mirrored and disposedrelative to the right leg of the wearer) or could be asymmetricaccording to an application. For example, a flexible exosuit could beconfigured to apply forces to an injured leg of a wearer but not to theopposite leg of the wearer. Other configurations of a flexible exosuitare anticipated.

A flexible exosuit could be configured to apply forces and/or torques ata single joint or right/left pair of joints of a wearer. Such a flexibleexosuit could include elements covering/disposed proximate to parts ofthe wearer distant from the single joint or could only include elementscovering/disposed proximate to the single joint. Elements of theflexible exosuit configured to apply forces/torques to the single jointcould be disposed proximate to the single joint or could be disposedelsewhere and mechanically coupled to the single joint, e.g., through abelt, cable, gears, twisted-string transmission, and/or some othermethod. In some examples, a flexible exosuit could be configured toapply forces across the ankles of a wearer. For example, the flexibleexosuit could include a smart tendon exomuscle disposed on the back ofthe wearer's leg and configured to apply and/or transmit forces betweentwo actuated elements mechanically coupled to the wearer's calf andfoot, respectively. Elements of the STEM (e.g., a motor configured todrive a twisted string transmission) could be disposed near the ankle(e.g., on the back of the calf) or at other locations (e.g., attached toa belt worn by the wearer, and mechanically coupled to the ankle by atwisted string or cable transmission). Such a flexible exosuit couldinclude additional elements, e.g., batteries, controllers, sensors,disposed according to an application. For example, sensors of theflexible exosuit could be disposed across the leg and torso to enablegait detection, a battery powering the flexible exosuit could be locatedon a belt worn by the wearer, etc.

A flexible exosuit (e.g., 100) could be operated to enable a variety offunctions or modes of operation according to a variety of applications.In some applications, a flexible exosuit could have a mode of operationconfigured to reduce, monitor, and/or ‘dose’ fatigue during physicalactivity of a wearer. For example, the flexible exosuit could beoperated to detect and/or prevent the development of fatigue duringextended locomotion by the wearer. The flexible exosuit could act toextract, store, and/or inject energy to/from the legs of the wearer toreduce fatigue. Additionally or alternatively, the flexible exosuitcould act to extract energy from the wearer during a first period and toinject the stored energy back to the wearer during a second period to‘level’ the amount of exertion/fatigue the wearer experiences betweenthe first and second periods. Other configurations and modes ofoperations of a flexible exosuit to reduce, monitor, and/or ‘dose’fatigue during locomotion, climbing, carrying, or other extendedphysical activities of a wearer.

In some applications, a flexible exosuit could have a mode of operationconfigured to increase the strength of the wearer. For example, aflexible exosuit including elements to apply forces and/or torques tothe arms of the wearer and/or between the arms of the wearer and thetorso/legs of the wearer, the flexible exosuit could be operated toenable the wearer to lift objects heavier than and/or to apply forcesgreater than the wearer would naturally be capable. The flexible exosuitcould apply forces and/or torques to the legs of the wearer to allow thewearer to jump higher than the wearer would naturally be capable. Insome applications, the flexible exosuit could have a mode of operationconfigured to prevent injury of the wearer by applying protective forcesand/or torques to joints of the wearer and/or applying clutches tocompliant elements crossing joints of the wearer to prevent excessivejoint and/or muscle motion or velocity. Operation of the flexibleexosuit to prevent injury of the wearer could occur continuously and/orcould occur when sensors of the flexible exosuit detect a state of thewearer and/or of the environment indicating an increased probability ofthe wearer being injured. In some applications, a flexible exosuit couldhave a mode of operation configured to assist a wearer to coordinatehis/her actions with another wearer of a flexible exosuit or with someother information source. The flexible exosuit could coordinate theactivity of the wearer by applying forces and/or torques to joints ofthe wearer in time with the source of coordination information and/orapplying haptic information to the wearer (e.g., vibrating elements ofthe exosuit).

A flexible exosuit could have a mode of operation configured to provideinformation to and/or detect information from a wearer. For example,actuators of the flexible exosuit (e.g., twisted string actuators,exotendons, STEMs, EPAM actuators, vibration sources) could be operatedto indicate some information to the wearer. In one example, a sequenceof torque pulses could be applied to a joint of the wearer to indicate abattery status of the exosuit, or to indicate that the wearer shouldcheck a communications device. In another example, vibrating motors inthe flexible exosuit could indicate that the wearer was straying from acommanded pose, where the commanded pose is a pose the wearer couldassume to satisfy some objective, e.g., to minimize fatigue whilecrouching or standing. Motions, forces, or other mechanical outputs ofthe wearer could be detected by sensors and/or actuators of the flexibleexosuit. The detected motions could be used to control functions of theexosuit and/or to control other systems in communication with theflexible exosuit. For example, a certain gesture (e.g., tapping the leftfoot against the ground twice) could be detected by the flexible exosuitand used to as a command, e.g., to prepare the exosuit to assist thewearer in climbing a wall, or to send an all-clear signal to a remoteserver. Additionally or alternatively, the motions, forces, and othermechanical information about the wearer could be recorded for later use,e.g., biomechanical research, physical training, motion capture forentertainment, or some other application.

A flexible exosuit could have modes of operation configured to cause amovement of the wearer even in cases where the wearer is unable to moveor where the wearer is attempting to move in a manner contrary to themovement executed by the flexible exosuit. In an example, the wearercould be incapacitated, and the flexible exosuit could operate to movethe wearer to safety and/or to a source of emergency assistance. Inanother example, a limb or other portion of the wearer could be whollyor partially paralyzed, and the flexible exosuit could operate to movethe paralyzed portion of the wearer, e.g., to allow the wearer tolocomote. A flexible exosuit could be operated to enable rehabilitationof a wearer (e.g., when the wearer has experienced a stroke, spinal cordinjury, nerve damage, or some other injury or disease process),assisting weakened movements of the wearer and/or counteractingdisordered movements of the wearer.

A flexible exosuit could be operated in combination with some otherprosthetic system. For example, a wearer could be missing a limb, andthe flexible exosuit could operate in combination with a prosthetic wornby the wearer and configured to replace some of the function of themissing limb. The flexible exosuit could be integrated with theprosthetic, and could be configured to mount the prosthetic to thewearer and/or to transmit forces and/or torques between the prostheticand the wearer. In some example, information detected using sensorsand/or actuators of the flexible exosuit (e.g., information about theposture and movement of a leg of the wearer) could be used to operatethe prosthetic (e.g., a detected locomotor gait type, phase, speed, orother information from the leg of the wearer could be used to control aleg prosthetic to assume a configuration complementary to theconfiguration of the wearer's leg). Such a flexible exosuit couldadditionally be operated to optimize the movements of the wearer tocomplement the operation of the prosthetic during an activity (e.g.,altering a gait pattern of a wearer's leg to complement a pattern ofoperation of a leg prosthetic).

II. A Reconfigurable, Wearable Platform for Mechatronic Interfacing withthe Human Body

Flexible exosuits as described herein could act as standard,multi-purpose platforms to enable a variety of mechatronic, biomedical,human interface, training, rehabilitative, communications, and otherapplications. A flexible exosuit could make sensors, electronicallyoperated actuators, or other elements or functions of the flexibleexosuit available to remote systems in communication with the flexibleexosuit and/or a variety of applications, daemons, services, or othercomputer-readable programs being executed by processors of the flexibleexosuit. The flexible exosuit could make the actuators, sensors, orother elements or functions available in a standard way (e.g., throughan API, communications protocol, or other programmatic interface) suchthat applications, daemons, services, or other computer-readableprograms could be created to be installed on, executed by, and operatedto enable applications and/or modes of operation of a variety offlexible exosuits having a variety of different configurations. The API,communications protocol, or other programmatic interface made availableby the flexible exosuit could encapsulate, translate, or otherwiseabstract the operation of the flexible exosuit to enable the creation ofsuch computer-readable programs that are able to operate to enablefunctions and/or operational modes of a wide variety ofdifferently-configured flexible exosuits.

Additionally or alternatively, the flexible exosuit could be modular inits hardware configuration (i.e., actuators, sensors, or other elementscould be added or subtracted from the flexible exosuit to enableapplications, functions, and/or operational modes of the flexibleexosuit). This modularity could be reflected in the processors,operating systems, or other controllers configured to operate theelements of the flexible exosuit. That is, the controllers of theflexible exosuit could determine the hardware configuration of theflexible exosuit dynamically (akin to “plug-and-play”) and could adjustthe operation of the flexible exosuit relative to the determined currenthardware configuration of the flexible exosuit. Additionally oralternatively, the controllers of the flexible exosuit could be providedwith information describing the hardware configuration of the flexibleexosuit. This operation could be performed in a way that was ‘invisible’to computer-readable programs (e.g., computer-readable programsdescribing methods to enable an operating mode of the flexible exosuit)accessing the functionality of the flexible exosuit through astandardized programmatic interface. For example, the computer-readableprogram could indicate to a controller of the flexible exosuit, throughthe standardized programmatic interface, that a specified level oftorque was to be applied to an ankle of a wearer of the flexibleexosuit. The controller of the flexible exosuit could responsivelydetermine a pattern of operation of actuators, based on the determinedand/or provided hardware configuration of the flexible exosuit,sufficient to apply the specified level of torque to the ankle of thewearer.

Further, the use of electronically operable actuators (e.g., twistedstring actuators, EPAM actuators and/or haptic feedback elements,exotendons, electrostatic clutches, electrolaminates, etc.) could enablethe use of standard driving electronics and communications and/or powerbusses and interconnects to enable function and operating modes of aflexible exosuit according to a variety of specialized applicationsand/or configurations. For example, individual configurations offlexible exosuits could be specified related to individual wearers,environments, sets of applications, or other considerations. The cost,time, or other resources required to design and enable such anindividual flexible exosuit could be reduced by using such standarddriving electronics, and communications and/or power busses, electricaland/or mechanical interconnects, controllers, computer-readable controlprograms, or other standardized aspects enabling the fabrication,programming, and operation of a flexible exosuit. Further, the use ofsuch standard hardware and software could enable common applications,services, drivers, daemons, or other computer-readable programs to becreated to enable functions or operating modes of a variety of flexibleexosuits having a variety of respective configurations. A flexibleexosuit configured in this way (i.e., to act as a standardized platformfor a variety of applications) could operate according to a variety ofdifferent operating modes to enable a respective variety of applicationsof a flexible exosuit. For example, different modes of operation couldcorrespond to the wearer walking, running, jumping, lifting, loadcarrying, climbing, cycling, exercising, training, controlling a virtualavatar, controlling a tele-robotic system, or some other application oractivity of the wearer. In some examples, an operating mode (enabled,e.g., by a computer-readable program installed on the flexible exosuit)could not be compatible with the hardware configuration of the flexibleexosuit. For example, the operating mode could require actuators to becoupled to the flexible exosuit and to be configured to apply a certainminimum amount of torque to the ankle of a wearer. If a control systemof the flexible exosuit determines that the hardware configuration isinsufficient to enable the operating mode, the control system coulddisable the operating mode and/or effect the operating mode at a reducedlevel. The control system could additionally or alternatively indicatethat the hardware of the flexible exosuit was unable to fully enable theoperating mode (e.g., by operating haptic elements or other actuators ofthe flexible exosuit) and/or indicate specifications and configurationsof actuators that the wearer could acquire and install on the flexibleexosuit to enable the operating mode. Other modes of operation andconfigurations of a flexible exosuit and elements thereof areanticipated.

III. Exotendons, Electrostatic Clutches, Electrolaminates,Controllable-Compliance Elements, Energy Storage and Recovery Elements,and Other Configurations of Electrostatic Metamaterials

A flexible exosuit could include a plurality of flexible elementscapable of being loaded under tension. In some applications, it could beuseful for a flexible exosuit to include such tensile flexible elementswhere the elements had a compliance that was able to be electronicallymodulated (e.g., switched or clutched between two or more states). Forexample, the compliance of the element could have two or more discretevalues, or a continuous range of values, according to an electronicoperation of the element. Additionally or alternatively, the tensileflexible element could have a zero- or low-compliance state (i.e.,transmitting longitudinal tension while exhibiting substantially nolongitudinal strain) and an infinite- or high-compliance state (i.e.,substantially incapable of transmitting tension while exhibitingwhatever effective strain is required for such) and the tensile flexibleelement could change states according to electronic operation of theelement. Such electronically-controlled-compliance tensile flexibleelements could be implemented using electrostatic clutches (i.e.,clutches configured to use electrostatic attraction to generatecontrollable forces between clutching elements), and are termedexotendons in this disclosure. Exotendons as described herein can becomposed of flexible or rigid elements according to an application.Further, exotendons can be thin and conformal to curved or flatsurfaces.

FIG. 2A is a cross-sectional illustration of an example exotendon 200 a.The exotendon includes first and second endplates 210 a, 220 a that areconfigured to be mechanically coupled to first and second elements ofsome other mechanism or apparatus (e.g., flexible and/or rigidforce-transmitting elements of a flexible exosuit) according to anapplication. The exotendon 200 a includes first and secondlow-compliance sheets 230 a, 235 a rigidly coupled to the first andsecond endplates 210 a, 220 a, respectively. The first and secondlow-compliance sheets 230 a, 235 a are locally substantially parallel toeach other, and have a surface of overlap 250 a. The first and secondlow-compliance sheets 230 a, 235 a additionally include respectiveconductive electrodes 232 a, 237 a coated in respective insulator layers234 a, 239 a such that there is no direct high-conductance path betweenthe first and second conductive electrodes 232 a, 237 a. The exotendon200 a additionally includes first and second high-compliance elements240 a, 245 a connecting the first low-compliance sheet 230 a to thesecond endplate 220 a and the second low-compliance sheet 235 a to thefirst endplate 210 a, respectively. Similar configurations of two ormore locally flat sheets that are configured to clutch togetherelectrostatically (e.g., by including conductive electrodes disposed onthe locally flat sheets) could be termed electrolaminates.

When the electrodes are uncharged, the exotendon 200 a will generallyact as a compliant element with a compliance corresponding to thecompliance of the first low-compliance sheet 230 a in series with thefirst high-compliance element 240 a in parallel with the secondlow-compliance sheet 235 a in series with the second high-complianceelement 245 a.

Application of a high voltage between the first and second conductiveelectrodes 232 a, 237 a causes the development of an attractive forcebetween the conductive electrodes 232 a, 237 a and/or other elements ofthe exotendon 200 a, acting to ‘clutch’ the first and secondlow-compliance sheets 230 a, 235 a together by applying a normal forcebetween first and second low-compliance sheets 230 a, 235 a across thesurface of overlap 250 a. The insulator layers 234 a, 239 a have aspecified resistivity allowing a specified low level of current to flowdirectly between the conductive electrodes 232 a, 237 a. When operatedwith high voltage in this way, the exotendon 200 a will generally act asa relatively non-compliant element with a compliance corresponding to afirst fraction of the compliance of the first low-compliance sheet 230 ain series with a second fraction of the compliance of the secondlow-compliance sheet 235 a, where the first and second fractions arerelated to the degree of overlap of the first and second sheets 230 a,235 a.

Elements of the exotendon 200 a or other similar clutched-complianceelements could be configured in a variety of ways and include a varietyof materials. Further, the ordering and presence of the layers ofexotendon 200 a (i.e., first low-compliance sheet 230 a>first conductiveelectrode 232 a>first insulator layer 234 a>second insulator layer 239a>second conductive electrode 237 a>second low-compliance sheet 235 a)is meant as an illustrative example. Other orderings of conductivelayers, low-compliance sheets, and insulator layers are anticipated. Insome examples, only one insulator layer may be present. In someexamples, a conductive electrode and low-compliance sheet may beincorporated as a single element (i.e., a low-compliance, conductivematerial). The compositions, dimensions, and relative ordering of layersof an exotendon could be specified to achieve a desired level ofclutching force (e.g., due to Coulombic attraction, Johnsen-Rahbekeffects, or other physical principles), overall compliance in clutchedand/or un-clutched states, or other considerations. An exotendon couldadditionally or alternatively be configured and operated to clutchand/or control a torsional compliance, a shear compliance, mechanicalimpedance, or some other mechanical property of the exotendon. In someexamples, the high-compliance elements 240 a, 245 a could be part ofprotective packaging of the exotendon or could be omitted altogether. Insome examples, additional layers, materials, or other elements could beincluded. For example, the low-compliance sheets 230 a, 235 a couldinclude and/or be adhered to a fiber-reinforced or other variety ofadhesive tape. The conductive electrodes 232 a, 237 a could include avariety of materials (e.g., aluminum, magnesium, copper, silver, gold,conductive carbon nanotubes) disposed by a variety of methods (e.g.,chemical vapor deposition (CVD), physical vapor deposition (PVD),sputtering, adhesive bonding, lithography) onto respectivelow-compliance sheets 230 a, 235 a the could include a variety ofmaterials (e.g., Mylar, polyimide, carbon fiber, polymers, crystals,liquid crystals). For example, the first conductive electrode 232 a andfirst low-compliance sheet 230 a could together be a sheet of aluminizedMylar. Additionally or alternatively, the conductive electrodes 232 a,237 a and respective low-compliance sheets 230 a, 235 a could be asingle material. For example, the second conductive electrode 237 a andsecond low-compliance sheet 235 a could together be a sheet ofconductive polyimide. In other examples, the second conductive electrode237 a and second low-compliance sheet 235 a could together be a sheet ofpolymer or other material impregnated with a conductive substance, e.g.,conductive carbon nanotubes or other conductive particles.

The insulator layers 234, 239 a could include a variety of materialsaccording to an application. In some examples, the insulator layers 234,239 a could be polyurethane or some other polymer material. A conductivematerial, dipole, or other electrically-active element could be added tothe polymer material to effect specified properties of the insulatorlayers 234, 239 a (e.g., resistivity, breakdown voltage, dielectricconstant, degree of charge migration at the surface of overlap 250 a,high level of surface charge density at the surface of overlap 250 awhen the conductive electrodes 232 a, 237 a are charged) to effectcertain properties of the exotendon 200 a (e.g., clutching force,clutching pressure, coefficient of friction or degree of stiction at thesurface of overlap 250 a). For example, the insulator layers 234, 239 acould be layers of polyurethane containing metal oxide particles orsalts (e.g., tetrabutylammonium perchlorate).

The composition and operation of the exotendon 200 a could be determinedby desired operational characteristics of elements of the exotendon 200a and/or the exotendon 200 a as a whole. Durability, strength, number ofactuation cycles to failure, operating voltage, clutch and un-clutchedcompliance levels, clutching strength (e.g., the pressure exertedbetween elements of the exotendon 200 a when the exotendon is operatedto clutch), insulator layer resistivity, clutch switching time, andother properties could be specified according to an application of theexotendon 200 a. For example, when the insulator layer is composed ofpolyurethane impregnated with a metal oxide, the exotendon 200 a couldbe clutched using a voltage of 400 volts and 5 microamps applied to theconductive electrodes, and this applied voltage could result in apressure of 7.5 pounds per square inch between the two sides of theclutch of the exotendon 200 a. Further, the exotendon 200 a could switchbetween the clutched and un-clutched state in less than 20 millisecondsand could be operated to clutch and to subsequently un-clutch more than1000000 times before failing.

The exotendon 200 a could be operated as a clutched-compliance element,switching between two or more states having two or more respectiveoverall levels of compliance according to an application. In someexamples, the exotendon 200 a could be part of a flexible exosuit, andcould be operated thusly to increase the efficiency of locomotion of awearer by providing an appropriate additional compliance across a jointof the wearer during specified phases of locomotion. Additionally oralternatively, the exotendon 200 a could be operated to reduce thecompliance of the exotendon to protect a joint of a wearer, e.g., duringa fall, while being operated during other periods to have a highercompliance so as to interfere less with the movement of the joint. Insome examples, the high-compliance elements 240 a, 245 a could have avery high compliance, or could be omitted (thus having an effectively‘infinite’ compliance), allowing the exotendon 200 a to be operated as aswitchable tensile flexible element. For example, such an exotendon 200a included in an arm of a flexible exosuit could be operated to allowunrestricted arm movement (i.e., to transmit substantially no tension)during a first period of time. The exotendon 200 a could be operatedduring a second period of time to be substantially noncompliant (i.e.,acting as a rigid element capable of transmitting longitudinal forces)during a second period, to transmit some of a load carried by the armsuch that the wearer could expend less energy to carry the load. Theratio between the compliance of the exotendon 200 a during the firstperiod and the compliance of the exotendon 200 a during the secondperiod could be greater than 100:1. Other applications, configurations,and operations of the exotendon 200 a are anticipated.

In some examples, the exotendon 200 a could be connected in series witha spring, to allow the spring to be clutched to transmit forces (e.g.,to/from a body of a wearer) during a first period of time and totransmit substantially no forces during a second period of time. Forexample, the exotendon 200 a could be connected in series with a springbetween the calf and the foot of a wearer, such that the exotendon 200 aand spring could be operated to apply an extensor torque to the ankle ofthe wearer. The exotendon 200 a could be clutched following contact ofthe heel of the user with the ground during locomotion. The clutchedspring could then be ‘charged’ with elastic potential energy as the userflexes their ankle. The ‘stored’ elastic potential energy could bereleased to the ankle of the wearer as the wearer extends their anklebefore lifting their foot from the ground; this storage and release ofmechanical energy from/to the ankle of the wearer could increase theefficiency of the locomotion of the wearer. The exotendon 200 could beun-clutched following the lifting of the wearer's foot from the ground,such that the exotendon 200 a and spring did not substantially affectthe rotation and/or torque at the wearer's ankle while the wearer's footwas not in contact with the ground. Other configurations and patterns ofuse of a spring connected in series with an exotendon are anticipatedaccording to an application. Further, the spring connected in the serieswith the exotendons could be implemented as an element of the exotendon,e.g., the high-compliance elements 240 a, 245 a of exotendon 200 a.

The exotendon 200 a could additionally be operated to dissipate energy.A high voltage could be applied between the first and second conductiveelectrodes 232 a, 237 a such that an attractive force develops betweenthe conductive electrodes 232 a, 237 a. The high voltage could becontrolled such that the first and second low-compliance sheets 230 a,235 a were only partially ‘clutched;’ that is, an external force appliedbetween the first and second endplates 210 a, 220 a could be sufficientto cause the first and second low-compliance sheets 230 a, 235 a toslip, allowing a displacement between the first and second endplates 210a, 220 a to increase. In the process, some of the energy applied to theexotendon 200 a by the force between the first and second endplates 210a, 220 a could be dissipated by frictional heating of the surface ofoverlap 250 a as the first and second low-compliance sheets 230 a, 235 aslip against each other.

The exotendon 200 a illustrated in FIG. 2A is intended as an example ofa broader class of controlled-compliance exotendons that could beincluded in a variety of applications and apparatus. Exotendons couldinclude more than two low-compliance sheets. Exotendons could includemultiple exotendons configured in series and/or parallel to enablecertain applications. Exotendons could be flexible and/or compliant innon-longitudinal directions, and could be configured to flexibly conformto a curved surface.

The exotendon 200 a could be operated, as part of a flexible exosuitworn by a wearer, to deliver haptic information to the wearer. Theexotendon 200 a, while under some nominal tension applied by segment ofthe body of the wearer and/or by elements of the flexible exosuit, couldbe operated to repeatedly clutch and un-clutch (and/or repeatedly clutchand partially un-clutch) by changing a voltage applied to the conductiveelectrodes 232 b, 236 b. A repeated change in compliance of and/or forcetransmitted by the exotendon 200 a, mechanically coupled into the skinand/or body segments of the wearer by elements of the flexible exosuit,could cause the wearer to experience a haptic sensation. In someexamples, the exotendon 200 a could be operated to indicate a physicalaction and/or to indicate a change in a physical action to be performedby the wearer. In an example, the exotendon 200 a could be activatedacross the knee of a wearer to indicate to the wearer that a step shouldbe initiated using the leg of which the knee is a part. In anotherexample, a wearer could be locomoting using a gait that is likely toresult in fatigue and/or injury, and exotendons of a flexible exosuitworn by the wearer could indicate ways the wearer could alter their gait(e.g., by activating exotendons in directions of joint torque opposite‘good’ directions of motion, to stimulate the wearer away from ‘bad’motions) to reduce the rate of fatigue and/or the probability of injury.

An exotendon could include two low-compliance sheets, as exotendon 200 adoes, or could include more low-compliance sheets. Some of the more thantwo low-compliance sheets could have conductive electrodes and/orinsulator layers on both sides. The more than two low-compliance sheetscould be operated similarly to exotendon 200 a. The additionallow-compliance sheets could enable higher overall strength, higherstrain to slip, or other properties to such an exotendon. Thelow-compliance sheets could have a specified compliance, and theconductive electrodes on the more than two low-compliance sheets couldbe operated to only clutch a subset of the more than two low-compliancesheets together. In this way, the overall compliance of the exotendoncould be electronically actuated to have a number of values, where thevalue of the overall compliance of the exotendon is related to which ofthe more than two low-compliance elements are clutched together. Otherconfigurations of an exotendon are anticipated.

FIG. 2B is a cross-sectional illustration of an example exotendon 200 b.The exotendon includes first and second endplates 210 b, 220 b that areconfigured to be mechanically coupled to first and second elements ofsome other mechanism or apparatus (e.g., flexible and/or rigidforce-transmitting elements of a flexible exosuit) according to anapplication. Similar to exotendon 200 a, exotendon 200 b includes firstand second low-compliance sheets 231 b, 235 b rigidly coupled to thesecond and first endplates 220 b, 210 b, respectively. The first andsecond low-compliance sheets 231 b, 235 b are locally substantiallyparallel to each other, and have a surface of overlap 250 b. The firstand second low-compliance sheets 231 b, 235 b additionally includerespective conductive electrodes 232 b, 236 b coated in respectiveinsulator layers 233 b, 237 b such that there is no directhigh-conductance path between the first and second conductive electrodes232 b, 236 b. The exotendon 200 b additionally includes first and secondhigh-compliance elements 240 b, 245 b connecting the firstlow-compliance sheet 231 b to the first endplate 210 b and the secondlow-compliance sheet 235 b to the first endplate 220 b, respectively.The exotendon 200 b is flexible, and is wrapped around a bar 215 b. As aresult, the exotendon 200 b can be operated to transmit non-parallel,non-collinear forces between external elements that are coupled to thefirst and second endplates 210 b, 220 b by wrapping around the bar 215 band by transmitting forces into the bar 215 b.

An exotendon could be configured that included multiple independentlyactuated exotendons (e.g., exotendon 200 a) connected in series. FIG. 2Cis a cross-sectional illustration of an example exotendon 200 c. Theexotendon includes first and second endplates 210 c, 220 c that areconfigured to be mechanically coupled to first and second elements ofsome other mechanism or apparatus (e.g., flexible and/or rigidforce-transmitting elements of a flexible exosuit) according to anapplication. Exotendon 200 c includes three independently actuatablesub-exotendons 201 c, 203 c, 205 c configured similarly to exotendon 200c and connected by series endplates 212 c, 214 c. That is, eachsub-exotendon 201 c, 203 c, 205 c includes two low-compliance sheetsthat are configured to be electrostatically clutched together. Further,each low-compliance sheet is connected directly to a first endplate andindirectly to a second, opposite endplate through an element having aspecified compliance. The first sub-exotendon 201 c includes firstspecified compliance elements 251 c, the second sub-exotendon 203 cincludes second specified compliance elements 252 c, and the thirdsub-exotendon 205 c includes third specified compliance elements 253 c.The overall compliance of the exotendon 200 c is related to thecompliance of the three sub-exotendons 201 c, 203 c, 205 c connected inseries.

Each of the sub-exotendons 201 c, 203 c, 205 c can be independentlyclutched. That is, when clutched, a sub-exotendon has a first overallcompliance substantially related to the compliance of the low-compliancesheets of the clutched sub-exotendon. Further, when unclutched, thesub-exotendon has a second overall compliance substantially related tothe compliance of the low-compliance sheets of the sub-exotendon inseries with the compliance of the specified compliance elements of thesub-exotendon. Thus, depending on the actuation of the threesub-exotendons 201 c, 203 c, 205 c, the overall compliance of theexotendon 200 c could be controlled to have one of eight differentvalues.

The exotendon 200 c could be operated (i.e., the sub-exotendons 201 c,203 c, 205 c could be actuated) to effect a specified compliance betweenfirst and second elements of some other mechanism or apparatus (e.g.,elements of a flexible exosuit). For example, the compliance of theexotendon 200 c, when configured to apply forces across a joint of awearer of a flexible exosuit, could be operated to increase theefficiency of locomotion by the wearer by optimizing the impedance ofthe joint or operated according to some other application. Note that theillustrated exotendon 200 c is only one example of an exotendonincluding independently actuated sub-exotendons connected in series; ingeneral, an exotendon could include more or fewer than threesub-exotendons. Further, the sub-exotendons could be configuredsimilarly to or differently from the sub-exotendons 201 c, 203 c, 205 caccording to an application. Note that, where an exotendon includes Nindependently actuated sub-exotendons, the sub-exotendons could beactuated such that the overall compliance of the exotendon could becontrolled to have one of 2^N different levels, depending on therespective compliances of the low-compliance sheets and specifiedcompliance elements of each of the sub-exotendons.

FIGS. 2D and 2E show cross-sectional and front views, respectively, ofexotendons 210 d, 212 d, 214 d, 216 d connected to force-transmittingelements 220 d, 222 d, 224 d of a flexible exosuit 200 d being worn by awearer 230 d. Each of the exotendons 210 d, 212 d, 214 d, 216 d ismechanically connected to neighboring force-transmitting elements 220 d,222 d, 224 d. The exotendons 210 d, 212 d, 214 d, 216 d could beconfigured and/or operated similarly to the exotendons describedelsewhere herein (e.g., 200 a, 200 b, 200 c). The exotendons 210 d, 212d, 214 d, 216 d could be connected to the force-transmitting elements220 d, 222 d, 224 d to prevent the exotendons 210 d, 212 d, 214 d, 216 dfrom rubbing on the skin of the wearer 230 d. In some examples, thiscould be accomplished by configuring the force-transmitting elements 220d, 222 d, 224 d as standoffs to prevent relative motion between the skinof the wearer 230 d and surfaces of the exotendons 210 d, 212 d, 214 d,216 d. The exotendons 210 d, 212 d, 214 d, 216 d could be operated tomodulate the way forces are transmitted between the force-transmittingelements 220 d, 222 d, 224 d to enable functions of the flexible exosuit200 d. For example, the exotendons 210 d, 212 d, 214 d, 216 d could beoperated to modulate the compliance of the flexible exosuit 200 and/orthe wearer 230 to increase the efficiency of locomotion, lifting orcarrying an object, or some other activity of the wearer. The exotendons210 d, 212 d, 214 d, 216 d could additionally or alternatively beoperated to store and release energy, reposition the force-transmittingelements 220 d, 222 d, 224 d, or other functions. Exotendons 210 d, 212d, 214 d, 216 d and force-transmitting elements 220 d, 222 d, 224 dconfigured similarly to those illustrated in FIGS. 2D and 2E onapplications other than a flexible exosuit 200 d; for example, suchelements could be part of a robot, an assistive device, a prosthetic, anexosuit configured to be used by an animal, or some other device orsystem.

Note that exotendons described herein are intended as non-limitingexamples of configurations and applications of exotendons. Two or moreadjacent, locally parallel electrostatic clutching elements of anexotendon could be rectangular sheets or could have some other shape,and could be curved, wrapped, helical, cylindrical, or some othergeometry according to an application. The distribution of conductivematerial on the locally parallel clutching elements could be uniform(i.e., evenly distributed across the locally parallel clutchingelements) or could have some pattern, e.g., parallel linear,cross-hatching, fractals, or some other pattern according to anapplication. The exotendons could further include clutching elementsthat are not locally parallel sheets; that is, the exotendons couldinclude other electrostatic clutching materials and configurations ofmaterials. For example, the exotendons could include arrays oflow-compliance electrostatic latches disposed on a high-compliance basematerial such that the exotendons had a first overall compliance relatedto the compliance of the base material when the latches are not latchedand a second compliance related to the compliance of the latches whenthe latches are latched. For example, exotendons or otherelectrostatically-operated clutched-compliance elements could beconfigured as described in U.S. Pat. No. 8,436,508.

An exotendon can be configured to have some specified clutching force;that is, forces applied to the exotendon when the exotendon is beingoperated to assume a clutched state (e.g., a low-compliance state) willnot cause the exotendon to increase in length or otherwise slip when theapplied forces have a magnitude less than the clutching force. Anexotendon could be operated in combination with other elements toincrease the effective magnitude of the clutching force when theexotendon is operated in a clutched state. For example, friction betweenthe exotendon and/or a cable or other element coupled to the exotendoncould be used to increase the effective clutching force of theexotendon, e.g., by employing the capstan effect.

FIG. 3A shows a flexible exotendon 310 a wrapped around a cylindricalcapstan 324 a. A first end of the exotendon 310 a is connected to afirst actuated element 322 a that is rigidly mechanically coupled to thecapstan 324 a. A second end of the exotendon is connected via a cable330 a to a second actuated element (not shown). When the exotendon 310 ais not being operated to clutch (i.e., a voltage is not applied betweentwo or more conductive elements within the exotendon 310 a such that theoverall compliance of the exotendon 310 a is high), the length of theexotendon 310 a is able to be increased by tensile forces applied to thecable 330 a. When the exotendon 310 a is being operated to clutch (i.e.,the overall compliance of the exotendon 310 a is caused to become low byapplication of voltage between conductive elements of the exotendon 310a), forces applied to the cable 330 a that have a magnitude less thanthe magnitude of a capstan hold force cannot cause the length of theexotendon 310 a to increase. Forces applied to the cable 330 a cause anincrease in a normal force between the exotendon 310 a and the capstan324 a. This increased normal force results in an increased shear forcebetween the exotendon 310 a and the capstan 324 a that is due tofriction and that opposes the forces applied to the cable 330 a. Thecapstan hold force is related to the clutching force of the exotendon310 a, the coefficient of friction between the exotendon 310 a and thecapstan 324 a, and the angle across which the exotendon 310 a contactsthe surface of the capstan 324 a. The capstan hold force can be greaterthan the clutching force of the exotendon 310 a, such that the exotendon310 a and capstan 324 a, in combination, could be able to resist forcesapplied to the cable 330 a that have greater magnitude than could beresisted by the exotendon 310 a without the capstan 324 a.

FIG. 3B shows a flexible exotendon 310 b. A first end of the exotendon310 b is connected to a first actuated element 322 b that is rigidlymechanically coupled to a cylindrical capstan 324 b. A second end of theexotendon is connected via a cable 330 b to a second actuated element(not shown). The cable 330 b is wrapped around the capstan 324 bmultiple times. When the exotendon 310 b is not being operated to clutch(i.e., a voltage is not applied between two or more conductive elementswithin the exotendon 310 b such that the overall compliance of theexotendon 310 b is high), the length of the exotendon 310 b is able tobe increased by tensile forces applied to the cable 330 b. When theexotendon 310 b is being operated to clutch (i.e., the overallcompliance of the exotendon 310 b is caused to become low by applicationof voltage between conductive elements of the exotendon 310 b), forcesapplied to the cable 330 b that have a magnitude less than the magnitudeof a capstan hold force cannot cause the length of the exotendon 310 bto increase. Forces applied to the cable 330 b cause an increase in anormal force between the cable 330 b and the capstan 324 b. Thisincreased normal force results in an increased shear force between thecable 330 b and the capstan 324 b that is due to friction and thatopposes the forces applied to the cable 330 b. The capstan hold force isrelated to the clutching force of the exotendon 310 b, the coefficientof friction between the cable 330 b and the capstan 324 b, and thenumber or times the cable 330 b wraps around the capstan 324 b. Thecapstan hold force can be greater than the clutching force of theexotendon 310 b, such that the exotendon 310 b, cable, 330 b, andcapstan 324 b, in combination, could be able to resist forces applied tothe cable 330 b that have greater magnitude than could be resisted bythe exotendon 310 b without the cable 303 b and capstan 324 b.

The capstan hold force of the combination of the exotendon 310 b, cable,330 b, and capstan 324 b of FIG. 3B could be specified by choosing theradius of the capstan 324 b, the number of times the cable 330 b iswrapped around the capstan 324 b, the coefficient of friction betweenthe cable 303 b and the capstan 324 b, or other features. For example,more than one cable 330 b could be connected to the exotendon 310 b andwrapped around the capstan 324 b or around some other element rigidly orotherwise coupled to the first actuated element 322 b.

The configurations illustrated in FIGS. 3A and 3B are intended asillustrative examples of configurations of exotendons and elementsconnected to the exotendons having frictive surfaces such that shearforces at the frictive surfaces effectively multiply the clutching forceof the exotendons. Other configurations are anticipated. In someexamples, other rigid elements than cylindrical capstans could be infrictive contact with exotendons and/or elements connected toexotendons. For example, an exotendon could be in contact with a curvedsurface of a rigid force-transmitting element (RFTE) of a flexibleexosuit, such that the exotendon in combination with the RFTE could beoperated to resists greater forces than the exotendon could resist ifnot in contact with the RFTE. The shape of those other rigid elementscould be specified to maximize the ratio of the capstan holding force tothe clutching force of the exotendon or according to some otherconsideration.

IV. Twisted String Transmissions for Mechanical Actuation

Many applications require linear actuators configured to apply forcesand/or effect changes in displacement between two actuated elements.Twisted string actuators are a class of actuators that translate atorque and/or rotation into a force and/or displacement by twisting astring made of two or more flexible strands. Alternatively, a singlestrand can be folded in half and twisted about itself, resulting in atwisted string able to be incorporated into a twisted string actuator.Rotation of the string causes the two or more strands to twist,shortening the string and/or creating a force between the ends of thestring. Such a string could have a first end connected to a firstactuated element and a second end connected (via e.g., a thrust bearing)to a second actuated element to convert rotation (e.g., by a motorcoupled to a segment or end of the string) of a segment or end of thestring into displacement of and/or force between the first and secondactuated elements. Further, because the twisted string can be flexible,a twisted string actuator can allow for actuation around curved and/orflexible elements. A twisted string actuator as described herein can beincorporated into a flexible exosuit to enable functions of the flexibleexosuit or can be used in a variety of other applications.

FIG. 4A illustrates a twisted string actuator (TSA) 400 configured toapply a force across the ankle of a wearer 405. The force generated bythe TSA 400 is coupled to the wearer 405 through a flexible mesh grip440 worn around the calf of the wearer 405 and a rigid footplate 445attached to the foot of the wearer 405. The TSA 400 includes an actuatorhead 410, a transmission tube 420, and a twisted string 430. A first end433 of the twisted string 430 is rigidly connected to the rigidfootplate 445 such that both torques and forces transmitted through thetwisted string 430 are transmitted to the rigid footplate 445. A secondend (435 in FIG. 4B) is attached to a rotor or other component of theactuator head 410 such that forces transmitted through the twistedstring 430 are transmitted to the flexible mesh grip 440 through theactuator head 410 and/or transmission tube 420 and such that torquestransmitted through the twisted string 430 are transmitted through therotor or other component to the actuator head 410 through a rotaryactuator, e.g., a motor.

Thus, the TSA 400 can be operated to produce a force and/or induce areduction of displacement between the flexible mesh grip 440 and therigid footplate 445 by applying a torque and/or rotation to the secondend of the twisted string 430. This force and/or displacement couldcause the ankle of the wearer 405 to extend and/or to apply a forceand/or torque to the environment of the wearer 405 (e.g., to the groundbeneath the wearer 405). Additionally or alternatively, the TSA 400could be actuated to reduce a force between the flexible mesh grip 440and the rigid footplate 445 by reducing, removing, or otherwise changinga torque applied to the second end of the twisted string 430.

The TSA 400 could additionally or alternatively be operated to be drivenby motions, forces, and/or torques applied between the flexible meshgrip 440 and the rigid footplate 445 by the wearer 405. For example, therotary actuator in the actuator head 410 could be operated to extractenergy from rotation of the twisted string 430 caused by the applicationof force between the flexible mesh grip 440 and the rigid footplate 445.This energy could be stored by some other system connected to the rotaryactuator. Additionally or alternatively, the TSA 400 could be operatedto act as a brake on changes in displacement between the flexible meshgrip 440 and the rigid footplate 445 (caused, e.g., by movement of theankle of the wearer 405).

TSA 400, as illustrated in FIG. 4A, is attached to a first actuatedelement that is flexible (i.e., flexible mesh grip 440) and to a secondactuated element that is rigid (i.e., rigid footplate 445) andconfigured to apply forces and/or torques across the ankle of a wearer405. However, a general TSA could be configured to operate acrossdifferent joints or to be operated in other applications requiringlinear or other actuation. Further, a general TSA could be mechanicallycoupled to other combinations of rigid, flexible, semi-rigid, orotherwise configured actuated elements than flexible and rigid first andsecond actuated elements, respectively.

Transmission tube 420 is a single, straight, rigid tube. However, ageneral TSA could be differently configured, as described in detailbelow. A transmission tube could be straight, curved, serpentine, orhave some other shape according to an application. Additionally oralternatively, a transmission tube could be flexible in some way; insome examples, the transmission tube could withstand longitudinal forceswhile allowing the transmission tube to be bent, for example, around ajoint that flexes during operation of the TSA. That is, the transmissiontube and twisted string partially contained therein could be configuredanalogously to the outer housing and inner cable, respectively, of aBowden cable.

Further, the transmission tube 420 and/or elements attached thereto(e.g., flexible mesh grip 440) could be configured to be adjustable,such that properties of the TSA 400 are adjustable. For example, thetransmission tube 420 could include lockable and/or actuated telescopingelements such that the overall length of the transmission tube 420(i.e., the length between the actuator head 410 and the end of thetransmission tube 420 from which the twisted string 430 emerges) couldbe changed and/or controlled to control a range-of-motion, atransmission ratio, or some other property of the TSA 400. Additionallyor alternatively, the transmission tube 420 and/or the flexible meshgrip 440 could be configured to allow the relationship between thetransmission tube 420, the flexible mesh grip 440, and the rigidfootplate 445 to be changed (i.e., to bring the end of the transmissiontube 420 proximate to the rigid footplate 445 closer to the rigidfootplate 445) to control a range-of-motion, a transmission ratio, orsome other property of the TSA 400. Other methods and types ofreconfiguration and/or actuation of the TSA 400 are anticipated.

FIG. 4B is a close-up cross-sectional view of elements of the actuatorhead 410, transmission tube 420, and twisted string 430 of the twistedstring actuator (TSA) 400 illustrated in FIG. 4A. TSA 400 includes ahousing 460 that contains part of the transmission tube 420, part of thetwisted string 430 (including first and second strands 430 a, 230 b;FIG. 4B illustrates the second end 435 of the twisted string 430), aload cell and encoder 445, a thrust bearing 440, a transmission block470, a slip clutch 455, and a motor 450.

The housing 460, transmission tube 420, load cell and encoder 445,stator elements of the thrust bearing 440, and stator elements of themotor 450 are rigidly mechanically coupled. The second end 435 of thetwisted string 430, the transmission block 470, and a first end of theslip clutch 455 are rigidly mechanically connected. A second end of theslip clutch 455 and rotor elements of the motor 450 are rigidlyconnected.

The motor 450 could be operated to generate a torque between the housing460 and the second end of the slip clutch 455. This torque could betransmitted through the slip clutch 455 and the transmission block 470to the twisted string 430, resulting in the TSA 400 applying a torqueand/or force between the flexible mesh grip 440 and the rigid footplate445. Similarly, the motor 450 could be operated such that a rotation ofthe rotor of the motor 450 resulted in a change in displacement betweenthe flexible mesh grip 440 and the rigid footplate 445.

The slip clutch could be configured such that the torque transferredbetween the motor 450 and the transmission block 470 does not exceed aspecified torque level. The specified torque level could be chosen orset such that a force applied between the flexible mesh grip 440 and therigid footplate 445 by TSA 400 does not exceed a specified force level.The specified force level could be related to the specified torque leveland a transmission ratio of the TSA 400 related to the length of thetwisted string 430 and the pitch of the twist of the strands 430 a, 430b of the twisted string 430.

The load cell and encoder 445 are configured to measure the forcetransmitted through and the rotation of the second end 435 twistedstring 430. The load cell could include piezoelectric elements, straingauges, or other elements configured to transduce the force transmittedfrom the second end 435 of the twisted string 430 into the transmissiontube 420 and actuator head 410 into a signal or value able to be used asan indicator of that transmitted force (e.g., an electrical voltage).The encoder could include optical or other elements capable of measurethe absolute and/or relative rotation of the second end 435 of thetwisted string 430 directly and/or indirectly (e.g., by detectingabsolute or relative rotation of the transmission block 470, twistedstring 430, and/or a rotor of the thrust bearing 440).

For example, the rotor of the thrust bearing 440 could include a gratingthat is curved radially around the axis of the thrust bearing 440 andthat extends into the load cell and encoder 445. The encoder couldinclude at least one light emitter and at least two light detectorsarranged such that a beam of light from the at least one emitter couldbe detected by the at least two detectors, unless a slat of the gratingof the thrust bearing 440 is interposed between one or more of the atleast two detectors and the at least one emitter. A pattern of occlusionof the at least two detectors over time could be detected and used todetermine an angle and direction of rotation of the thrust bearing 440rotor (and by proxy, the second end 435 of the twisted string 430).Other types of sensors and sensed elements of rotating members areanticipated, e.g., magnetic sensors, optical sensors, and electricalcontacts in contact with corresponding conductive trace patterns.Additionally or alternatively, the motor 450 could be operated to detectrotation of the motor 450 (e.g., by detecting back EMF on coils of themotor 450 and/or counting a number and pattern of coil activations) andfrom the detected rotation of the motor 450 to infer rotation of thesecond end 435 of the twisted string 430.

Information from the load cell and encoder 445 could be used to operateTSA 400, for example, to operate the TSA 400 using feedback. Forexample, a controller could operate the motor 450 based on forces and/orrotations detected using the load cell and encoder 445 to generate aconstant force in the twisted string, a constant rotation of the secondend 435 of the twisted string 430, or some other specified pattern ofactuation of the TSA 400. Additionally or alternatively, a controllercould be configured to derive other detectable parameters of the TSA420, flexible mesh grip 440 and/or rigid footplate 445. For example, thecontroller could be configured to determine a rotation rate of thesecond end 435 of the twisted string 430 corresponding to a specifiedrate of change of linear displacement between the flexible mesh grip 440and the rigid footplate 445 based on a stored, known, or otherwisedetermined current length and/or level of twist of the twisted string430. The controller could then operate the TSA 400 to effect thespecified rate of change of linear displacement by operating the motor450 to effect the rotation rate corresponding to the rate of change oflinear displacement. Other methods of operation of the TSA 400 areanticipated.

The TSA 400 illustrated in FIGS. 4A and 4B includes elements configuredsuch that the direction of a force transmitted by the twisted string 430is in the direction of and aligned with the axis of rotation of themotor 450, the thrust bearing 440, and the second end 435 of the twistedstring 430. This alignment could reduce wear and fatigue of the twistedstring 430 compared to other configurations. A TSA could additionallyinclude a grommet or other element a specified distance along the axisof rotation and configured to ensure that the direction of a forcetransmitted by the second end 435 of the twisted string 430 is in thedirection of and aligned with the axis of rotation. Note that thedirection of a force transmitted by sections of the twisted string 430that are on the distal side of the grommet relative to the actuator head410 could be different than the direction of the axis of rotation.Additionally or alternatively, a TSA could include a gimbal and aconstant-velocity or universal joint and could be configured such that athrust bearing, second end of a twisted string, or other rotationalelements of the TSA were coupled to the gimbal such that the axis ofrotation of the rotational elements of the TSA are aligned with thedirection of a force transmitted by the second end of the twistedstring. This configuration could reduce wear and fatigue of the twistedstring compared to other configurations.

The TSA 400 could be configured to be partially disassembled. Forexample, the motor 450 and/or elements of the slip clutch 455 could beremoved from the actuator head 410 without removing other elements,e.g., the twisted string 430 and transmission block 470. In anotherexample, the transmission block 470, elements of the slip clutch 455 andthrust bearing 440 and the twisted string 430 could be removed withoutfully disassembling the TSA 400. This partial disassembly could allowfor broken elements (e.g., a twisted string 430 that has been flexed,stressed, fatigued, or otherwise utilized to failure) to be replacedquickly and easily (i.e., field-stripped). Additionally oralternatively, this partial disassembly could allow for componentshaving different properties to be swapped out of the TSA 400 accordingto changing conditions, wearers, and/or applications. For example, a setof twisted strings could be fabricated such that individual twistedstrings of the set are configured for respective individual wearers(e.g., wearers having respective different heights, calf lengths, footlengths, or other properties). A twisted string of the set correspondingto properties of the wearer 405 could be quickly and easily installed inthe TSA 400. Additionally or alternatively, the TSA 400 could beoperated using a first twisted string having properties (transmissionratio, length, stroke length) specified to enable basic operation of theTSA 400 for a broad population of wearers. The wearer 405 could operatethe TSA 400 and sensors (e.g., the load cell 445, encoder 440, or othersensors) could be operated to determine an optimal transmission ratio,length, stroke length, or other properties of the TSA 400. The secondtwisted string having properties corresponding to the determined optimalproperties could be quickly and easily installed in the TSA 400. Motors450, slip clutches 455, or other elements could be similarly matched tothe wearer 455 and quickly and easily installed in the TSA 400.

The transmission block 470 connected the twisted string 430 to otherelements of the TSA 400 within the actuator head 410 and/or transmissiontube 420. The transmission block 470 transmits linear forces from thetwisted string 430 through the thrust bearing 440 and load cell andencoder 445 to the transmission tube 420 and/or actuator head 410. Thetransmission block 470 transmits torque from the motor 450 (via the slipclutch 455) to the twisted string 430. Forces, especially time-varyingcyclical forces, applied between the transmission block 470 and thestrands 430 a, 430 b of the twisted string 430 can cause the strands 430a, 430 b to fail at the second end 435 in or near the transmission block470 before the strands 430 a, 430 b fail at other locations along thetwisted string 430.

Individual strands 430A, 430 b of the twisted string 430 enter thetransmission block 470 and come into contact with the transmission block470 along a contact surface 437. The ends of the individual strands430A, 430 b rigidly attach to the structure of the transmission block470 by being tied, welded, clamped, or by some other fixation method.The contact surface 437 has an overall radius of curvature such thatloads between the individual strands 430A, 430 b and the transmissionblock 470 are distributed substantially evenly across the contactsurface 437. That is, a surface on which an individual strand 430A, 430b contacts the transmission block 470 can be approximated by an arc of acircle having a radius equal to the radius of curvature. Additionally oralternatively, the contact surface 437 could correspond to a compoundcurve in three dimensions. The shape of the contact surface 437 could bespecified to reduce the rate of fatigue and/or the probability offailure of the strands 430 a, 430 b of the twisted string 430 comparedto other configurations of the transmission block 470. Additionally oralternatively, the strands 430A, 430 b could be tied together using aknot (e.g., a single or triple fisherman's knot) and looped around asmooth rigid or semi-rigid element (e.g., a cylinder). The smoothelement could be incorporated in the TSA 400 in the place of thetransmission block 470. Additionally or alternatively, the smoothelement could be incorporated into the transmission block 470.

In some examples, the twisted string 430 could be fabricated from asingle strand folded in half and twisted about itself, such that thestrands 430 a, 430 b correspond to respective halves of the singlestrand. In those examples, the region of the folding of the singlestrand corresponds to the second end 435 of the twisted string 430. Thehalves of the single strand could be folded around a securing elementthat is mechanically coupled to rigid footplate 445. The securingelement could be a cylinder or some other smooth rigid or semi-rigidelement configured to minimize the concentration of stress in thestrands 430 a, 430 b of the twisted string. The radius of the cylinderor other smooth element could be a specified value large enough that,when the TSA 400 is operated to cause maximum twist of the twistedstring 430, the strands 430 a, 430 b leaving the cylinder or othersmooth element form an angle greater than 90 degrees.

Properties of the twisted string 430 and of the individual strands 430a, 430 b of the twisted string 430 could be specified to satisfy someconstraint(s) and/or to have some property(s) according to anapplication. For example, a diameter and composition of the strands 430a, 430 b could be chosen such that the twisted string 430 had aspecified strength, fatigue resistance, transmission ratio, compliance,or some other property or properties. In some examples, the strands ofthe twisted string could be wholly or partially composed ofultra-high-molecular-weight polyethylene or some other high strength,low bending radius, low internal friction, high stiffness material.

The twisted string 430 could be configured and/or include additionalelements to reduce the rate of fatigue and/or the probability of failureof the twisted string 430. For example, the individual strands 430 a,430 b near the second end 435 could have a coating or cladding to smooththe transition between contact and non-contact with the transmissionblock 470. For example, the ends of the individual strands 430 a, 430 bcould be wholly or partially encased in and/or coated with PTFE, anotherfluoro-polymer, and/or some other low-friction material. To reducefatigue of and/or reduce the chance of failure of the twisted string430, low-friction or otherwise protective coatings and/or claddingscould be applied along part of or the entire length of the individualstrands 430 a, 430 b. Additionally or alternatively, a lubricant couldbe applied to the twisted string 430, e.g., a silicone lubricant. Alow-friction protective material could be interposed between theindividual strands 430 a, 430 b of the twisted string 430 to reducefriction between the individual strands 430 a, 430 b and to preventsurface roughness or other aspects of the individual strands 430 a, 430b from damaging the individual strands 430 a, 430 b during use of theTSA 400. For example a long, narrow strip of Teflon sheet (or some otherlow-friction material) could be interposed between the individualstrands 430 a, 430 b.

The fabrication of the individual strands 430 a, 430 b and/or thetwisted string 430 could be executed in such a way as to reduce the rateof fatigue and/or the probability of failure of the strands 430 a, 430 bof the twisted string 430. In some examples, the strands 430 a, 430 bcould individually be fabricated to have a helical geometry such thatthe individual strands 430 a, 430 b experienced minimal internal strainwhen assembled into the twisted string 430 and when the twisted string430 is actuated to ‘mid-stroke’ (i.e., the twisted string 430 is rotatedsuch that the length of the twisted string 430 was some length betweenthe full length of the un-twisted twisted string 430 and a lengthcorresponding to some maximal functional twist of the twisted string430). This could be accomplished by assembling a bundle of fibers. Afirst twist could be applied to the bundle of fibers. The bundle offibers could then be folded in half about an attachment point (e.g., asmooth cylinder rigidly coupled to the rigid footplate 445) such thatthe point of the folding becomes the second end 435 of the twistedstring 430. The two halves of the bundle (identical with respectivestrands 430 a, 430 b) could then be twisted in about each other to formthe twisted string 430. The ends of the bundle could be tied togetherand secured to the transmission block 470. The fibers of the twistedstring 430 can exhibit minimal strain at some level of twist and/orlength; this level of twist and/or length can be related to themagnitude of the first twist. Thus the magnitude of the first twistcould be specified in order to fabricate a twisted string having aspecific transmission ration, length, stroke length, or combination ofthese properties related to the specified magnitude of the first twist.In some examples, the strands 430 a, 430 b could be assembled into thetwisted string 430 (i.e., tied, welded, clamped, or otherwise attachedto string-terminating elements, e.g., the transmission block 470) andthe twisted string 430 could be stretched and heated such that thelengths of the individual strands 430 a, 430 b become more identical.

A twisted string actuator (TSA) could include a string having twostrands, like the strands 430 a, 430 b of the twisted string 430 of TSA400, or could include more than two strands. The arrangement of the twoor more strands could be controlled and/or specified. In some examples,the arrangement of the two or more strands could be controlled by theconfiguration of a transmission block (e.g., 470) or by the way in whichends of the strands opposite the transmission block are attached to eachother and/or to an actuated element. For example, a transmission blockcould be configured such that the transmission block causes four strandsof a twisted string attached to the transmission block to assume asquare configuration, a diamond configuration, a triangularconfiguration (i.e., three of the four strands form a triangle, and thefourth strand is maintained at the center of the triangle), or someother configuration according to an application. Additionally oralternatively, a twisted string could include one or more spaces alongthe length of the twisted string to control the arrangement of the twoor more strands of the twisted string. A spacer could include strips ofTeflon or other low-friction substances to additionally reduce thefriction between the individual strands of the twisted string as thetwisted string is twisted.

TSA 400 is one embodiments of a twisted string actuator (TSA) asdescribed herein. Other configurations of TSAs, including alternate,additional, fewer, and/or differently configured components areanticipated. A TSA could include multiple twisted strings, differentnumber(s) of strands, multiple motors, twisted strings actuated by tworotational actuators (i.e., a rotational actuator coupled to each end ofthe twisted string), more than one transmission tube, differentlyconfigured transmission tubes, different locations and/or means ofattachment to actuated elements, or other configurations according to anapplication. For example, FIGS. 5A-5G illustrates alternateconfigurations of twisted string actuators (TSAs) 500 a-500 g.

FIG. 5A illustrates a TSA 500 a attached to first 510 a and second 520 aactuated elements such that the TSA 500 a could be operated to apply aforce and/or change a displacement between the first 510 a and second520 a actuated elements. The TSA 500 a includes a transmission tube 550a rigidly coupled to the first actuated element 510 a and a stator of amotor 540 a. The first actuated element 510 a is rigidly attached to thetransmission tube 550 a and the motor 540 a near the connection betweenthe transmission tube 550 a and the motor 540 a. A first end of atwisted string 530 a is mechanically coupled to the second actuatedelement 520 a. A rotor of the motor 540 a is coupled to a second end ofthe twisted string 530 a such that the motor 540 a can be operated toapply a torque and/or rotation to the second end of the twisted string530 a such that the TSA 500 a applies a force and/or changes adisplacement between the first 510 a and second 520 a actuated elements.

FIG. 5B illustrates a TSA 500 b attached to first 510 b and second 520 bactuated elements such that the TSA 500 b could be operated to apply aforce and/or change a displacement between the first 510 b and second520 b actuated elements. The TSA 500 b includes a transmission tube 550b rigidly coupled to the first actuated element 510 b and a stator of amotor 540 b. The first actuated element 510 b is rigidly attached to thetransmission tube 550 b near the end of the transmission tube 550 bopposite the motor 540 b. A first end of a twisted string 530 b ismechanically coupled to the second actuated element 520 b. A rotor ofthe motor 540 b is coupled to a second end of the twisted string 530 bsuch that the motor 540 b can be operated to apply a torque and/orrotation to the second end of the twisted string 530 b such that the TSA500 b applies a force and/or changes a displacement between the first510 b and second 520 b actuated elements.

FIG. 5C illustrates a TSA 500 c attached to first 510 c and second 520 cactuated elements such that the TSA 500 c could be operated to apply aforce and/or change a displacement between the first 510 c and second520 c actuated elements. The TSA 500 c includes a stator of a motor 540c rigidly coupled to the first actuated element 510 c. A first end of atransmission tube 550 c is rigidly coupled to a rotor of the motor 540c. A first end of a twisted string 530 c is mechanically coupled to thesecond actuated element 520 c. A second end of the twisted string 530 cis mechanically coupled to a second end of the transmission tube 550 c.A motor 540 b can be operated to apply a torque and/or rotation to thefirst end of the twisted string 530 b through the transmission tube 550c such that the TSA 500 c applies a force and/or changes a displacementbetween the first 510 c and second 520 c actuated elements.

FIG. 5D illustrates a TSA 500 d attached to first 510 d and second 520 dactuated elements such that the TSA 500 d could be operated to apply aforce and/or change a displacement between the first 510 d and second520 d actuated elements. The TSA 500 d includes a first rigidtransmission tube 551 d rigidly coupled to a flexible transmission tube553 d and a stator of a motor 540 d. The flexible transmission tube 553d is configured to transmit torques and/or forces along its length andto be flexible in directions perpendicular to its length (similar to theouter housing of a Bowden cable). The first actuated element 510 a isrigidly attached to a second rigid transmission tube 552 d which is inturn rigidly coupled to an end of the flexible transmission tube 553 dopposite the end of the flexible transmission tube 553 d connected tothe first rigid transmission tube 551 d. A first end of a twisted string530 d is mechanically coupled to the second actuated element 520 d. Arotor of the motor 540 d is coupled to a second end of the twistedstring 530 d such that the motor 540 d can be operated to apply a torqueand/or rotation to the second end of the twisted string 530 d such thatthe TSA 500 d applies a force and/or changes a displacement between thefirst 510 d and second 520 d actuated elements. The flexibletransmission tube 553 d could enable the TSA 500 d to be operatedconformably along a partially curved surface or other element (i.e., theflexible transmission tube 553 d could conform to the curved aspect ofthe partially curved surface) and/or to be operated while the flexibletransmission tube 553 d is flexed, e.g., the flexible transmission tube553 d crosses a joint or hinge and enables operation of the TSA 500 dwhile the hinge or joint flexes.

FIG. 5E illustrates a TSA 500 e attached to first 510 e and second 520 eactuated elements such that the TSA 500 e could be operated to apply aforce and/or change a displacement between the first 510 e and second520 e actuated elements. The TSA 500 e includes a flexible transmissiontube 552 e rigidly coupled to a rigid transmission tube 551 e and astator of a motor 540 e. The flexible transmission tube 552 e isconfigured to transmit torques and/or forces along its length and to beflexible in directions perpendicular to its length (similar to the outerhousing of a Bowden cable). The first actuated element 510 e is rigidlyattached to the rigid transmission tube 551 e near an end of the rigidtransmission tube 551 e opposite the end of the rigid transmission tube551 e connected to the flexible transmission tube 552 e. A first end ofa twisted string 530 e is mechanically coupled to the second actuatedelement 520 e. A rotor of the motor 540 e is coupled to a second end ofthe twisted string 530 e such that the motor 540 e can be operated toapply a torque and/or rotation to the second end of the twisted string530 e such that the TSA 500 e applies a force and/or changes adisplacement between the first 510 e and second 520 e actuated elements.The flexible transmission tube 552 e could enable the TSA 500 e to beoperated conformably along a partially curved surface or other element(i.e., the flexible transmission tube 552 e could conform to the curvedaspect of the partially curved surface) and/or to be operated while theflexible transmission tube 552 e is flexed, e.g., the flexibletransmission tube 552 e crosses a joint or hinge and enables operationof the TSA 500 e while the hinge or joint flexes.

FIG. 5F illustrates a TSA 500 f attached to first 510 f and second 520 factuated elements such that the TSA 500 f could be operated to apply aforce and/or change a displacement between the first 510 f and second520 f actuated elements. The TSA 500 f includes a flexible transmissiontube 552 e rigidly coupled to the first actuated element 510 f and astator of a motor 540 f. The flexible transmission tube 550 f isconfigured to transmit torques and/or forces along its length and to beflexible in directions perpendicular to its length (similar to the outerhousing of a Bowden cable). The first actuated element 510 f is rigidlyattached to the flexible transmission tube 550 f near the end of theflexible transmission tube 550 f opposite the motor 540 f. A first endof a twisted string 530 f is mechanically coupled to the second actuatedelement 520 f. A rotor of the motor 540 f is coupled to a second end ofthe twisted string 530 f such that the motor 540 f can be operated toapply a torque and/or rotation to the second end of the twisted string530 f such that the TSA 500 f applies a force and/or changes adisplacement between the first 510 f and second 520 f actuated elements.The flexible transmission tube 550 f could enable the TSA 500 f to beoperated conformably along a curved surface or other element and/or tobe operated while the flexible transmission tube 550 f is flexed, e.g.,the flexible transmission tube 550 f crosses one or more joints orhinges and enables operation of the TSA 500 f while the hinges or jointsflex.

FIG. 5G illustrates a TSA 500 g and first 510 g and second 520 gactuated elements. The first 510 g and second 520 g actuated elementsare configured to rotate about an axis 515 g. TSA 500 g is attached tofirst 510 g and second 520 g actuated elements such that the TSA 500 gcould be operated to apply a torque and/or change an angle between thefirst 510 g and second 520 g actuated elements about the axis 515 g. TheTSA 500 g includes a first transmission tube 551 g rigidly coupled tothe first actuated element 510 g and a stator of a motor 540 g and asecond transmission tube 552 g rigidly coupled to the second actuatedelement 520 g and a first end of a twisted string 530 g. The TSA 500 gadditionally includes a spacing member 553 g configured to rotate aboutthe axis 515 g and connected to a grommet 555 g through which thetwisted string 530 g passes. A rotor of the motor 540 g is coupled to asecond end of the twisted string 530 g such that the motor 540 g can beoperated to apply a torque and/or rotation to the second end of thetwisted string 530 g such that the TSA 500 g applies a torque and/orchanges an angle between the first 510 g and second 520 g actuatedelements about the axis 515 g.

A TSA can include more than one string. TSAs can include additionalstrings configured in a variety of ways to enable additionalfunctionality and/or improve or control one or more operatingcharacteristics of the TSA. For example, including additional strings ina TSA could increase the strength, stroke length, usable lifetime,redundancy, or other characteristics of the TSA. Further, the TSA couldbe configured to enable differential operation of the strings of theTSA, enabling higher transmission ratios between the motor of the TSAand the linear actuation of the TSA, or other characteristics oroperational modes. A variety of TSAs including multiple strings areillustrated in FIGS. 6A-6E.

FIG. 6A illustrates a TSA 600 a attached to first 610 a and second 620 aactuated elements such that the TSA 600 a could be operated to apply aforce and/or change a displacement between the first 610 a and second620 a actuated elements. The TSA 600 a includes a stator of a motor 630a rigidly coupled to the first actuated element 610 a. The TSA 600 aadditionally includes first 640 a and second 645 a twisted strings thathave respective first ends mechanically coupled to the second actuatedelement 620 a. The TSA 600 a further includes first 642 a and second 647a gears mechanically coupled to the first actuated element 610 a suchthat the gears 642 a, 647 a are able to rotate relative to the firstactuated element 610 a but are unable to translate relative to the firstactuated element 610 a. The gears 642 a, 647 a are enmeshed with eachother and have an identical number of teeth such that a rotation of onegear is accompanied by an opposite and substantially equal rotation ofthe other gear. The second gear 647 a is mechanically coupled to asecond end of the second twisted string 645 a. A rotor of the motor 632a is coupled to the first gear 642 a and a second end of the firsttwisted string 640 a such that the motor 630 a can be operated to applyopposite and substantially equal torque and/or rotations to the secondends of the twisted strings 640 a, 645 a such that the TSA 600 a appliesa force and/or changes a displacement between the first 610 a and second620 a actuated elements.

FIG. 6B illustrates a TSA 600 b attached to first 610 b and second 620 bactuated elements such that the TSA 600 b could be operated to apply aforce and/or change a displacement between the first 610 b and second620 b actuated elements. The TSA 600 b includes a stator of a motor 630b rigidly coupled to the first actuated element 610 b. The TSA 600 badditionally includes a two sets of gears. A first set of gears includesfirst 642 b and second 647 gears that are mechanically coupled to thefirst actuated element 610 b such that the first set of gears 642 b, 647b are able to rotate relative to the first actuated element 610 b butare unable to translate relative to the first actuated element 610 b.The first set of gears 642 b, 647 b are enmeshed with each other andhave an identical number of teeth such that a rotation of one of thegears is accompanied by an opposite and substantially equal rotation ofthe other gear of the first set of gears 642 b, 647 b (i.e., the firstset of gears 642 b, 647 b has a gear ratio of unity). A second set ofgears includes third 644 b and fourth 649 gears that are mechanicallycoupled to the second actuated element 620 b such that the second set ofgears 644 b, 649 b are able to rotate relative to the second actuatedelement 620 b but are unable to translate relative to the secondactuated element 620 b. The second set of gears 644 b, 649 b areenmeshed with each other and have a different number of teeth such thata rotation of one of the gears is accompanied by an opposite andsubstantially different rotation of the other gear of the second set ofgears 644 b, 649 b (i.e., the second set of gears 644 b, 649 b has anon-unity gear ratio).

The TSA 600 b additionally includes first 640 b and second 645 b twistedstrings that have respective first ends mechanically coupled to thethird 644 b and fourth 649 b gears, respectively. The first 640 b andsecond 645 b twisted strings additionally have respective second endsmechanically coupled to the first 642 b and second 647 b gears,respectively. A rotor of the motor 632 b is coupled to the first gear642 b such that the motor 630 b can be operated to apply opposite andsubstantially equal torque and/or rotations to the second ends of thetwisted strings 640 b, 645 b. As a result of such rotations and/ortorques, first ends of the twisted strings 640 b, 645 b rotationsopposite each other and having a ratio related to the ratio of thenumber of teeth on the third gear 644 b and the number of teeth on thefourth gear 649 b. Further, these rotations can cause the TSA 600 b toapply a force and/or change a displacement between the first 610 b andsecond 620 b actuated elements. A transmission ratio of the TSA 600 bcould be defined as a ratio between a torque applied by the rotor 632 band the forces applied between the first and second actuated elements610 b, 620 b as a result of the torque. The transmission ratio of theTSA 600 b could be related to the gear ratio of the second set of gears644 b, 649 b and the length, degree of twist, or other factors relatedto the twisted strings 640 b, 645 b. This configuration could enable ahigher transmission ratio (between rotation/torque of the motor 632 band change of displacement/force between the first 610 b and second 620b actuated elements) than could be achieved without the second set ofgears 644 b, 649 b by allowing the twisted strings 640 b, 645 b toengage in a certain degree of rotation that is greater than the degreeof twisting of the twisted strings 640 b, 645 b.

In some examples, the first set of gears 642 b, 647 b could have anon-unity gear ratio and the second set of gears 644 b, 649 b could havea gear ratio of unity. In other examples, the first 642 b, 647 b andsecond 644 b, 649 b set of gears could both have respective gear ratiosthat were not unity. The gear ratio of the first set of gears 642 b, 647b could be the reciprocal of the gear ratio of the second set of gears644 b, 649 b (e.g., the first set of gears 642 b, 647 b could have agear ratio of 2:1, and the second set of gears 644 b, 649 b could have agear ratio of 1:2). The choice of the gear ratios of the respective setsof gears could be specified as reciprocal to balance a load, torque, orother consideration between elements of the TSA 600 b (e.g., to balancea strain experienced by thrust bearings that couple the gears withrespected actuated elements). Other configurations of the TSA 600 b areanticipated.

A TSA configured similarly to one or more of the TSAs described herein(e.g., TSAs 600 a, 600 b) could include additional twisted strings andrespective gears configured such that a torque and/or rotation could beapplied in common to all of the twisted strings of the TSA. Additionaltwisted strings could be added to increase a strength, fatigueresistance, lifetime, redundancy, or some other property of the TSA.Gears of the TSA could have one or more gear ratios to effect aspecified fixed or variable transmission ratio of the TSA. Additionallyor alternatively, the TSA could include additional gears or otherelements such that the torques and/or rotations were applied in commonto the twisted strings but such that the gears coupled to the stringsare not necessarily directly enmeshed with each other. For example, aTSA could be configured similarly to the TSA 600 a but could includegears that are linked by a chain drive such that a rotation of one gearis accompanied by a substantially equal rotation of a second gear in thesame direction as the rotation of the first gear. Other configurationsand additional elements are anticipated.

FIG. 6C illustrates a TSA 600 c attached to first 610 c and second 620 cactuated elements such that the TSA 600 c could be operated to apply aforce and/or change a displacement between the first 610 c and second620 c actuated elements. The TSA 600 c includes a stator of a motor 630c. The TSA 600 a additionally includes first 640 c and second 645 ctwisted strings that have respective first ends mechanically coupled tothe second actuated element 620 c and third 641 c and fourth 646 ctwisted strings that have respective first ends mechanically coupled tothe first actuated element 610 c. The first 640 c and second 645 ctwisted strings have opposite twist; for example, the first twistedstring 640 c could have an S-twist and the second twisted string couldhave a Z-twist. Further, the first 640 c and third 641 c twisted stringshave opposite twist and the second 645 c and fourth 646 c twistedstrings have opposite twist. The TSA 600 c further includes first 642 cand second 647 c gears mechanically coupled to the first actuatedelement 610 c such that the gears 642 a, 647 a are able to rotaterelative to the stator of a motor 630 c but are unable to translaterelative to the stator of a motor 630 c. The gears 642 c, 647 c areenmeshed with each other and have an identical number of teeth such thata rotation of one gear is accompanied by an opposite and substantiallyequal rotation of the other gear. The second gear 647 c is mechanicallycoupled to respective second ends of the second 645 c and fourth 646 ctwisted strings via a second rotor 634 c. A rotor of the motor 632 c iscoupled to the first gear 642 c and respective second ends of the first640 c and third 641 c twisted strings such that the motor 630 c can beoperated to apply opposite and substantially equal torque and/orrotations to the second ends of the twisted strings 640 c, 641 c and 645c, 646 c such that the TSA 600 c applies a force and/or changes adisplacement between the first 610 c and second 620 c actuated elements.Additionally or alternatively, the second rotor 634 c could be a rotorof the motor 630 c and the motor 630 c could be configured to drive boththe rotor 632 c and the second rotor 634 c. Further, the TSA 600 c canbe configured such that thrust or other bearings coupling the gears 642c, 647 c to the stator of a motor 630 c transmit substantially nolongitudinal forces (i.e., in the direction of the axes of the twistedstrings 640 c, 641 c, 645 c, 646 c), due to such forces beingsubstantially transmitted by the twisted strings 640 c, 641 c, 645 c,646 c and/or the rotor 632 c and second rotor 634 c. This could enablethe use of lower-friction bearings and/or higher efficiency operation ofthe TSA 600 c by reducing friction losses due to longitudinal forces onbearings included in the motor 630 c.

FIG. 6D illustrates a TSA 600 d attached to first 610 d and second 620 dactuated elements such that the TSA 600 d could be operated to apply aforce and/or change a displacement between the first 610 d and second620 d actuated elements. The TSA 600 d includes a stator of a motor 630d coupled to an armature 650 d such that the stator 630 d is able tomove along an axis between the first and second actuated elements 610 d,620 d but substantially unable to translate perpendicular to the axis orto rotate relative to the first and second actuated elements 610 d, 620d. The TSA 600 d additionally includes first 640 d and second 645 dtwisted strings that have respective first ends mechanically coupled toa rotor of the motor 632 d and respective second ends mechanicallycoupled to the first 610 d and second 620 d actuated elements,respectively. The first 640 d and second 645 d twisted strings haveopposite twists, e.g., the first twisted string 640 d could have anS-twist and the second twisted string 645 d could have a Z-twist.

The TSA 600 d can be operated to apply a force and/or change adisplacement between the first 610 a and second 620 a actuated elementsby applying a torque to the first ends of the twisted strings 640 d, 645d using the rotor 632 d. A transmission ratio between rotation of therotor 632 d and change in displacement between the first 610 a andsecond 620 a actuated elements can be related to the lengths, degrees oftwist, or other factors related to the twisted strings 640 d, 645 d. TSA600 d, including two twisted strings 640 d, 645 d driven by the samerotor 632 d, could be employed in an application to provide atransmission ratio, stroke length, or other property that could bedifficult to achieve using similar materials or components configured asa TSA having a single twisted string (e.g., TSA 600 a). The TSA 600 dcould be configured such that, at rest or at some other default state,twisted strings 640 d, 645 d have lengths, degrees or twist, or otherfeatures such that the transmission ratio of the TSA 600 d is aspecified value and such that the transmission ratio of the TSA 600 dchanges as the TSA 600 d is operated (e.g., as the rotor 632 d isrotated to effect a change in displacement between the first 610 a andsecond 620 a actuated elements) according to an application. Forexample, the transmission ratio of the TSA 600 d could be a minimumvalue when the twisted strings 640 d, 645 d are fully untwisted and thetransmission ratio of the TSA 600 d could increase as the twistedstrings 640 d, 645 d are rotated by the rotor 632 d.

Additionally or alternatively, the first 640 d and second 645 d twistedstrings could have opposite twist. The TSA 600 d, configured in thisway, could be operated to apply a force and/or change a displacementbetween the first 610 a and second 620 a actuated elements by applying atorque to the first ends of the twisted strings 640 d, 645 d using therotor 632 d. Further, the TSA 600 d can be configured such that thrustor other bearings coupling the rotor 632 d to the stator of the motor630 d transmit substantially no longitudinal forces (i.e., in thedirection of the axes of the twisted strings 640 d, 645 d), due to suchforces being substantially transmitted by the twisted strings 640 d, 645d and/or the rotor 632 d. This could enable the use of lower-frictionbearings and/or higher efficiency operation of the TSA 600 d by reducingfriction losses due to longitudinal forces on bearings included in themotor 630 d.

FIG. 6E illustrates a TSA 600 e attached to first 610 e and second 620 eactuated elements such that the TSA 600 e could be operated to apply aforce and/or change a displacement between the first 610 e and second620 e actuated elements. The TSA 600 e includes first 630 e and second635 e motor stators coupled to an armature 650 e such that the stators630 e, 635 e are able to move along an axis between the first and secondactuated elements 610 e, 620 e but substantially unable to translateperpendicular to the axis or to rotate relative to the first and secondactuated elements 610 e, 620 e. The TSA 600 e additionally includesfirst 640 e and second 645 e twisted strings that have respective firstends mechanically coupled to respective first 632 e and second 637 emotor rotors and respective second ends mechanically coupled to thefirst 610 e and second 620 e actuated elements, respectively.

The first and second motors 630 e, 635 e could be operated to applyrespective torques to respective second ends of respective twistedstrings 640 e, 645 e to effect a force and/or change in displacementbetween the first 610 e and second 620 e actuated elements. In someexamples, the twisted strings 640 e, 645 e could have respectivedifferent lengths, degrees or twist, or other features such that therespective transmission ratios of the twisted strings 640 e, 645 e aredifferent. The first 630 e, 632 e and second 635 e, 637 e could beconfigured and/or operated advantageously relative to the differentproperties of the twisted strings 640 e, 645 e. For example, the firststring 640 e could have a higher transmission ratio than the secondstring 645 e and the first motor 630 e, 632 e could have a higher torquecapacity and a lower positional bandwidth than the second motor 635 e,637 e. A TSA 600 e configured in this way could have better overallperformance (in terms of torque, positional bandwidth, or otheroperational properties) than a TSA including only the first twistedstring 640 e and motor 630 e, 632 e alone or the second twisted string645 e and motor 635 e, 637 e alone. Other configurations and operationsof TSA 600 e are anticipated.

FIG. 6F illustrates a TSA 600 f attached to first 610 f and second 620 factuated elements such that the TSA 600 f could be operated to apply aforce and/or change a displacement between the first 610 f and second620 f actuated elements. The TSA 600 f includes stator of a motor 630 frigidly coupled to the first actuated element 610 f. A first end of afirst twisted string 640 f is wrapped around and mechanically coupled tothe edge of a pulley 642 f. The pulley is configured to freely rotatebut not to translate relative to a third element 650 f. A second twistedstring 645 f is connected between an axle of the pulley 642 f and thesecond actuated element 620 f A rotor of the motor 630 f is coupled to asecond end of the first twisted string 640 f such that the motor 630 fcan be operated to apply a torque and/or rotation to the second end ofthe first twisted string 640 f such that the first twisted string 640 fapplies a torque and/or rotation to the pulley 642 f and to the end ofthe second twisted string 645 f such that the TSA 600 f applies a forceand/or changes a displacement between the first 610 f and second 620 factuated elements. A transmission ratio of the TSA 600 f (i.e., a ratiobetween a torque applied by the motor 630 f and a resulting forceapplied between the first 610 f and second 620 f actuated elementsand/or a ratio between a rotation of the rotor of the motor 630 f and aresulting change in displacement between the first 610 f and second 620f actuated elements) could be a transmission ratio of the first twistedstring 640 f multiplied by the transmission ratio of the second twistedstring 645 f. A TSA configured similarly to the TSA 600 f (i.e., havingtwisted strings wrapped around pulleys and configured to rotate thepulleys, and further having other twisted strings driven by the rotationof the pulleys) could include more than two stages (i.e., two or morepulleys and twisted strings attached thereto) and could have atransmission ratio equal to the product of the transmission ratios ofall of the twisted strings of the TSA multiplied together.

Further, the twisted string of a TSA can be configured in a variety ofways. The twisted string could include two strands, as describedelsewhere herein, or could include more than two strands. A twistedstring could be configured such that the two or more strands of thetwisted string were located at the same distance from a rotational axisof the string (where the rotational axis could be a local rotationalaxis for strings that are not straight, e.g., strings that are containedwithin Bowden cable housings and that are deformed about another objector otherwise not straight). To ensure that the strands of a twistedstring are located at the same distance from the rotational axis of thestring and/or for other purposes, spacers could be incorporated into thestring. In some examples, the spacers could be toroidal, disc-shaped, orotherwise configured rings or plates having holes through which thestrands of the twisted string could pass; the size, shape, andpositioning of the holes could be such that the strands could change anangle of twist (e.g., as the twisted string is rotated) but such thatthe strands could not change their positioning relative to each other(i.e., they would maintain a radial distance from a rotational axis ofthe string and they would maintain an angular relationship between eachother). Additionally or alternatively, the twisted string could includea central element that ensured that the strands of a twisted string arelocated at the same distance from the rotational axis of the stringand/or for other purposes. For example, one or more spheres, cylinders,or other-shaped objects could be localized in the center (i.e., centeredon a rotational axis) of the twisted string. The location of the objectsin the center of the twisted string could be maintained by having threeor more strands in the twisted string and/or by including grooves orrings in the objects to ensure a specified relationship between thestrands and the objects. Additionally or alternatively, the objectscould be held in place by an additional center strand that did notsubstantially act to transmit longitudinal forces of the twisted string.

Alternatively, the twisted string of a TSA could comprise a singlestrand that is folded in half about an attachment point. The two halvesof the strand then twist around each other to form the twisted string.

The material composition of the strands of the twisted string, and ofpossible lubricants, spacers, anti-friction coatings or shims, or otherelements of or relating to the twisted string could be specifiedaccording to an application. Material compositions and configurations oftwisted strings and elements thereof can be specified to enable acertain application and/or to ensure that the twisted string has aspecified value of a property, e.g., compliance or fatigue resistance.Generally, strands of a twisted string can be configured to have a lowcompliance (i.e., the twisted string will deform minimally in responseto longitudinal stress on the string) a high strength (i.e., the twistedstring will only fail when exposed to very high longitudinal stresses)and a small bending radius (i.e., the strands of the twisted string areable to be coiled very tightly, about a small radius, without failure).Further, strands of a twisted string can be configured (by having amaterial composition and/or being woven in a certain manner from fibers)to have a low external friction (i.e., the strand will move against anexternal object, e.g., another strand, with low friction) and lowinternal friction (i.e., sub-strands, fibers, or other elementscomposing the strand will move against each other with low friction).

In some examples, the strands could be composed ofultra-high-molecular-weight polyethylene (compositions of which aretraded under the trade name Dyneema). In some examples, individualstrands of the twisted string could include a low-friction coating,surface treatment, or cladding. For example, an individual strand couldbe clad in polytetrafluoroethylene (PTFE). Additionally oralternatively, sheets of low-friction material (e.g., sheets of PTFE)could be disposed between strands of a twisted string to reduce frictionbetween the strands, decreasing mechanical losses to heat and decreasingfatigue of the strands. In some examples, strands or other elements ofthe twisted strings could be coated, impregnated with, or otherwiseexposed to a lubricant. For example, a twisted string could be coated ina silicone lubricant. Other compositions and configurations of twistedstrings are anticipated according to applications of twisted strings inTSAs. In an example, a twisted string could be composed of Dynex 70 orDynex 75 and could be lubricated by silicone grease.

Individual twisted strings could be nested and connected together toform composite twisted strings. Such a composite twisted string,incorporated into a TSA, could enable an actuator having many of thebenefits of a non-nested twisted string while having a greater strokelength per unit string length. FIGS. 7A, 7B, and 7C illustrate a nestedtwisted string 700 (NTS) that includes an outer twisted string 710, aninner twisted string 720, and a cylinder 730. The cylinder 730 isconfigured to transmit compression and torsion from one end of thecylinder 730 to the other end while exhibiting substantially nodeformation. The outer twisted string 710 includes three strands 712,714, 716 each connected to four spacer rings 718 a, 718 b, 718 c, 718 d.A first spacer ring 718 a is connected to a first end of the cylinder730 and a second spacer ring 718 d could be connected to a firsttermination block or other element configured to transmit forces and/ortorques into the twisted string 700. The inner twisted string 720includes three strands 722, 724, 726 each connected to four spacer rings728 a, 728 b, 728 c, 728 d. A first spacer ring 728 a could be connectedto a second termination block or other element configured to transmitforces and/or torques into the twisted string 700 and a second spacerring 728 d is connected to a second end of the cylinder 730.

FIG. 7A shows a side view of the NTS 700 where the NTS 700 is fullyextended; that is, the strands 712, 714, 716, 722, 724, 726 of the outer710 and inner 720 twisted strings are substantially parallel anduntwisted. FIG. 7B shows a side view of the NTS 700 where the NTS 700 ispartially twisted. The overall length of the NTS 700 shown in FIG. 7B isless than the overall length of the NTS 700 in FIG. 7A. FIG. 7C shows atop view of the NTS 700, showing how the inner twisted string 720, outertwisted string 710, and cylinder 730 are coaxial about a rotational axisof the NTS 700.

Example NTS 700 includes inner 720 and outer 710 twisted strings thatare substantially similarly configured; that is, their lengths andstrand and spacer compositions and configurations are substantiallyidentical and the radius of the spacers is identical except for a smalldifference to accommodate the cylinder 730 and to accommodate the motionof the inner 720 and outer 710 twisted strings relative to each otherwhen the NTS 700 is twisted. As a result, the behavior of the NTS 700 inresponse to twisting (i.e., the degree of shortening, a transmissionratio) is substantially identical to another twisted string configuredsimilarly to either the outer 710 or inner 720 twisted strings that hasa total length equal to the sum of the lengths of the inner 720 andouter 710 twisted strings. As a result, the NTS 700 can provide thefunctionality of a non-nested twisted string while having a shorteroverall length.

Note that NTS 700 is intended only as an illustrative example of anested twisted string that could be applied to a TSA or to otherapplications. The relative lengths, relative radii, number of spacers,number of strands, and other properties of the twisted strings could bedifferent than those described herein. In some examples, one or both ofthe twisted string could lack spacers. For example, the inner twistedstring 720 and/or the outer twisted string 710 could be tightly wound,i.e., could have no spacers. Further, the inner diameter of the cylinder730 could be related to a maximum effective diameter of the innertwisted string 720 when the inner twisted string 720 is fully twisted.In some example, an NTS could include more than two twisted strings. Forexample, an NTS could include three twisted strings and two cylinders.The twisted cylinder could be a solid cylinder (like the illustratedcylinder 730) or could be a rigid or semi-rigid mesh, rings connected bybars or plates, or some other structure capable of transmittingcompressive forces and torques from one end of itself to another.

A TSA configured as described herein could enable a variety ofapplications by enabling high-performance flexible linear actuation(i.e., generation of tensile forces and changes in linear displacementbetween ends of a flexible or semi-flexible element, e.g., twistedstring). Such a TSA can enable transduction of energy from a rotationalactuator to a linear displacement at greater than 92%. Use of high-speedelectrical motors as the rotational actuator driving a twisted string ofsuch a TSA can enable the actuation of the TSA to change length from amaximum length to a minimum length (i.e., to change in length by thestroke length of the TSA) in less than 200 milliseconds. Further, theTSA could be operated to achieve a positional bandwidth greater than 5hertz for displacements on the order of the stroke length. Suchhigh-performance capabilities enable novel applications, for example,the actuation of a flexible exosuit to augment or assist the activitiesof a wearer.

V. Actuators, Sensors, Power Sources, User Feedback Elements, and OtherElements of an Exosuit System.

A flexible exosuit can include a variety of actuators, sensors, andother elements. The actuators could include the aforementionedexotendons and twisted string actuators or could include additional oralternate actuators. A flexible exosuit can additionally includefeedback and control elements for detecting information about the wearerand/or elements of the flexible exosuit and its environment and forindicating information to the wearer and/or some other person or systemmechanically or electronically coupled to the flexible exosuit.

A flexible exosuit could include hydraulic and/or pneumatic actuatorsand other elements to enable to the use of those actuators (e.g., fluidpumps, reservoirs). Actuators of the flexible exosuit could be coupledto other elements of the flexible exosuit and/or tissues of the wearerby a variety of transmission methods. For example, a rotational actuatorcould create a rotational torque that is translated into a linear forceby a drive screw, a ball screw, a cable wrapped around a driven drum, orsome other method. Further, transmissions may be included in theflexible exosuit to transmit a force and/or torque from one location inthe flexible exosuit to another location; e.g., a cable (possiblydisposed within a Bowden-cable style sheath) could be used to transmit alinear actuation from a location at one end of the cable to anotherlocation at the other end of the cable. For example, an exotendon couldbe connected via one or more cables that may be disposed within one ormore Bowden-cable style sheaths to two or more elements of a flexibleexosuit or other system to allow the exotendon to apply a controllercompliance between, store a mechanical energy from a change indisplacement between, or otherwise apply a force between the two or moreelements of the flexible exosuit.

A class of actuators that could be included in a flexible exosuitincludes electro-active polymers (EAPs) configured to transduceelectrical energy into mechanical energy. EAPs are polymer materialscontaining electro-active molecules, crystals, or other materials thatare orientable or otherwise capable of exhibiting a physical change whensubjected to an electric field, such that the EAP material deforms whenexposed to an electrical field. Conversely, the EAP material may producean electrical field when deformed by an external force, allowing forbidirectional transduction of mechanical and electrical energy.

EAPs can be included in electroactive polymer artificial muscles(EPAMs). EPAMs are actuators that include an EAP material and two ormore electrodes configured to transduce an electrical voltage and/orcurrent applied to the electrodes into a mechanical force/displacement,due to a deformation of the EAP caused by an electrical field around theelectrodes that is caused by the applied voltage and/or current. In anexample configuration, a thin sheet of EAP has an electrode disposed oneither side (i.e., the electrodes are opposite each other along theshort axis of the EAP). Application of a high voltage between the twoelectrodes causes the EAP to deform, becoming thinner and wider/longer.The EAP can also become thicker due to the applied voltage. Conversely,energy can be extracted from the EPAM from an externally appliedmechanical force and deformation. Additionally or alternatively, an EPAMand/or other element including EAP material could be configured andoperated as a mechanical sensor, detecting strain, force, or some othermechanical variable by transducing the mechanical variable into avoltage and/or current at electrodes of the EPAM or other elementincluding EAP material.

EPAMs could be included in a flexible exosuit to inject and/or sinkmechanical energy to/from elements of the flexible exosuit and/or thewearer. An EPAM could be employed as an alternative to a twisted stringactuator or could be employed in other applications. For example, achemical-burning engine could include an EPAM and/or EAP material toenable extraction of energy from combustion of a fuel by transducing amechanical deformation of the EPAM or EAP (due, e.g., to an increasedpressure in a volume due to combustion of the fuel) into an electricalenergy that could be used to power a flexible exosuit, or to power someother electrical system. Additionally or alternatively, otherelastomeric polymers could be included in in such a chemical-burningengine.

EPAMs could be employed in a flexible exosuit as haptic elements. Thatis, an EPAM could be disposed in a flexible exosuit such that the EPAMwas in direct or indirect mechanical contact with skin of the wearer.Application of patterns of electrical energy to the EPAM could causedeformation of the EPAM that could be mechanically coupled into the skinof the wearer, causing the wearer to experience a haptic sensation. Sucha haptic indication could be used to communicate a variety ofinformation to the wearer. In some examples, an alert could becommunicated to the wearer using an EPAM haptic element. In someexamples, an EPAM haptic element could be operated to indicate aphysical action and/or to indicate a change in a physical action to beperformed by the wearer. In an example, an EPAM haptic element could beactivated at the knee of a wearer to indicate to the wearer that a stepshould be initiated using the leg of which the knee is a part. Inanother example, a wearer could be locomoting using a gait that islikely to result in fatigue and/or injury, and EPAM haptic elements of aflexible exosuit worn by the wearer could indicate ways the wearer couldalter their gait (e.g., by activating EPAM haptic elements in directionsopposite ‘good’ directions of motion, to stimulate the wearer away from‘bad’ motions) to reduce the rate of fatigue and/or the probability ofinjury.

Other operations of EPAM or other haptic elements to indicateinformation to a wearer of a flexible exosuit are anticipated. Further,EPAM haptic elements need not be limited to application in flexibleexosuits, and may be used to enable a variety of applications, includingindication using a variety of wearable devices (e.g., watches,headbands), haptic feedback as part of a virtual reality device, hapticfeedback as part of a tele-robotic system, or other applications.Further, other devices could be incorporated into a flexible exosuit orother system to enable to haptic indication or other functions describedherein. For example, piezoelectric elements, vibrating elements (e.g.,motors driving off-axis masses), heating elements, electrodes configuredto inject safe and sense-able electrical currents into human skin, orother mechanical transducers or actuators. Additionally oralternatively, other actuators (e.g., exotendons, TSAs) of a flexibleexosuit or other system could be operated to provide haptic feedback toa user. For example, an exotendon could un-clutch and then quicklyre-clutch several times in a row, resulting in a series of momentarychanges in the force transmitted by the exotendon that could be detectedby a wearer of a flexible exosuit including the exotendon. Further, EPAMcould be used as an input device by transducing a force exerted by auser (e.g., by a user pressing on an EPAM using a fingertip) into anelectrical signal that could be detected by a controller or other systemof a flexible exosuit or other system.

A flexible exosuit could include a smart sole device. A smart soledevice is mechanically coupled to the sole of the foot of the wearer andincludes at least one mechanical transducer. The mechanical transducercould be operated to sense a force between the sole of the wearer andthe ground, to extract and/or inject mechanical energy from/into aninteraction between the sole of the wearer and the ground, to modulate acompliance of the smart sole, or some other mechanical function. Themechanical transducer could include a variety of transducing elements,including EPAM elements, piezo elements, hydraulic elements, pneumaticelements, or some other elements. The smart sole could include one ormany mechanical transducers arranged in a variety of ways. For example,the smart sole could include a hexagonal array of EPAM transducersacross the sole of the foot of the wearer. Electrolaminates (e.g.,exotendons) could also be included in a smart sole to enable functionsof the smart sole, e.g., to control the compliance of the smart sole.The smart sole could be operated in a variety of ways to enable avariety of applications.

In some examples, the one or more mechanical transducers could beoperated to generate a detected distribution of force between the soleand the ground during a step. This information could be used to diagnosea medical condition, to indicate a way for the wearer to alter theirgait according to some application (e.g., to increase the efficiency oflocomotion of the wearer, to decrease a probability of injury), or someother application. In some examples, the one or more mechanicaltransducers could be operated to indicate a physical action and/or toindicate a change in an a physical action to be performed by the wearer(e.g., to reduce the amount of force the wearer applies to the heelduring a step, to reduce the degree of a heel strike, to reduce theamount of force the wearer applies to the outer edge of the sole duringa step). In some examples, the one or more mechanical transducers couldbe operated to modulate a compliance of the one or more mechanicaltransducers to increase the efficiency with which the wearer locomotes(e.g., by matching an impedance between the foot of the wearer and theground that the wearer is locomoting on). Other operations andapplications of a smart sole are anticipated.

A flexible exosuit could include a wide variety of sensors. The sensorscould be configured to sense a wide variety of physical phenomena,including electrical fields, electrical current, magnetic fields,mechanical stress, mechanical strain, pressure, humidity,electromagnetic radiation, high-energy particles, acceleration,displacement, rotational acceleration, rotational velocity, angulardisplacement, or other phenomena. The detected physical phenomena couldbe related to one or more properties of the wearer, of the flexibleexosuit, and/or of the environment of the wearer and flexible exosuit.The sensors could be disposed at a variety of locations on the flexibleexosuit. For example, a set of accelerometers could be disposed in theflexible exosuit to enable detection of the acceleration (and by proxy,location and displacement) of segments of the wearer's body. The sensorscould be incorporated into other elements of the flexible exosuit. Forexample, electrodes of an exotendon could be used to detect displacementand/or force between actuated elements attached to either end of theexotendon by detected the capacitance between the two electrodes. Thecapacitance between the two electrodes could be related to the degree ofoverlap of the electrodes, which could in turn be related to the length,force, strain, or other properties of the exotendon. In another example,an encoder could detect rotation of a motor of a TSA; the rotation ofthe motor could be used to determine the length of the TSA based oninformation about the twisted string of the TSA.

The sensors could be configured and/or disposed to allow for a partialor complete determination of the kinematic state of the wearer and/orthe flexible exosuit. That is, the sensors could be configured to allowfor detection of the position, velocity, relative orientation, relativeorientation velocity, and other properties of some or all of thesegments of the body of the wearer and/or segments of the flexibleexosuit. The sensors could include accelerometers and/or gyroscopesconfigured such that the accelerometers and/or gyroscopes could detectmotion and acceleration of parts of a wearer's body. The accelerometersand/or gyroscopes could be microelectromechanical systems (MEMS) or someother kind of systems.

The sensors could include displacement sensors for measuring thedistance between two points (e.g., between two different elements of theflexible exosuit). The displacement sensors could be implemented in avariety of ways; for example, the sensors could include twosubstantially parallel plates that are free to move relative to eachother and that are connected to respective measured locations; thedisplacement between the measured locations could be related to a degreeof overlap of the parallel plates, which could in turn be related to acapacitance between the parallel plates that could be detected todetermine the distance between the measured locations. The parallelplates could be part of an exotendon. Additionally or alternatively, adisplacement between two locations actuated by a TSA could be determinedby detecting the rotation of the twisted string of the TSA. In someexamples, a displacement could be detected by detecting the capacitanceof an EPAM as the EPAM is deformed by changes in the displacement. Ajoint angle could be determined based on a detected displacement betweentwo locations on opposite sides of the joint. Additionally oralternatively, a joint angle could be detected by using a goniometerincluded in the flexible exosuit.

The flexible exosuit could include biosensors configured to detect oneor more properties of the body of the wearer of the exosuit. In someexamples, the flexible exosuit could include two or more electrodesdisposed on the skin of the wearer for detecting biopotentials or fordetecting other properties of the wearer. For example, electrodes couldbe used to detect an electromyogram (EMG) generated by muscles of thewearer beneath the skin. Additionally or alternatively, electrodes couldbe used to detect an electrocardiogram (ECG) or an electrooculogram(EOG) generated by the heart or eye(s), respectively, of the wearer.Additionally, a small current could be injected into the skin of thewearer using the electrodes to detect a Galvanic skin response (GSR), animpedance spectrum, or some other property of the skin. The biosensorscould include light emitters and light sensors configured to detect apulse and/or blood oxygen level of the wearer. Other biosensors could beincluded in the flexible exosuit. Further, the properties of the wearerdetected using the biosensors could be used to enable a variety ofdifferent applications, including health monitoring, fatigue dosing(i.e., altering the operation of the flexible exosuit to meter the rateat which the wearer becomes fatigued), control of the exosuit (e.g.,detecting a controlled muscle twitch of the user and using the detectionto change an operating mode of the flexible exosuit), or otherapplications.

A flexible exosuit could include additional elements. For example, theflexible exosuit could include one or more controllers operativelycoupled to one or more actuators, sensors, or other elements of theflexible exosuit such that the one or more controllers could operate theflexible exosuit based on one or more stored programs accessible to theone or more controllers. The flexible exosuit could additionally includebatteries, fuel cells, engines, solar cells, or other elements toprovide power to operate the flexible exosuit. The flexible exosuitcould include communications elements, including radios, Bluetoothtransceivers, WiFi transceivers, LTE or other cellular communicationsequipment, satellite uplinks, ZigBee transceivers, IRdA or other opticalcommunications elements, or some other components configured to enablecommunications between elements of the flexible exosuit (e.g., acontroller) and some remote system.

A flexible exosuit could include electroadhesive elements. That is, theflexible exosuit could include elements that could electrically modulatean electrostatic attraction between the elements and some other object.The other object could be another element of the exosuit, skin of thewearer of the exosuit, or an element of the environment of the exosuit(e.g., a rock face, a wall, a box).

FIG. 8A is a cross-sectional view of an electroadhesive element 800being operated to electrostatically adhere to an object 805. The object805 is substantially electrically neutral. The electroadhesive element800 includes first 810 and second 820 conductors embedded in anonconductive substrate 840. An insulator layer 830 is disposed on aface of the electroadhesive element 800 that is positioned against theobject 805. The application of a high positive voltage to the firstconductors 810 relative to the second conductors 820 causes positive andnegative charges in the object 807 to separate and to beelectrostatically attracted to the second 820 and first 810 conductors.This electrostatic attraction causes the electroadhesive element 800 toexperience a normal force against the object 805. This normal forcecould be allow the electroadhesive element 800 to adhere to the object805 and not to slip against the object 805 despite a perpendicular forceapplied between the object 805 and the electroadhesive element 800. Themagnitude of perpendicular force that could be applied without slippingcan be related to the magnitude of the electrostatic normal force and acoefficient of friction between the insulator layer 830 and the surfaceof the object 805.

The electroadhesive element 800 could be operated to allow for elementsof a flexible exosuit to skin of the wearer to transmit forces fromelements of the flexible exosuit (e.g., exotendons, TSAs) into tissuesof the wearer. Further, such adhesion could be electronicallycontrolled, allowing the adhesion to be turned off when the flexibleexosuit was not transmitting forces to tissues of the wearer. In someexamples, the electroadhesive element 800 could be used to adhereobjects to the flexible exosuit. For example, the electroadhesiveelement 800 could be used to adhere a pack, weapon, or other equipmentreversibly to the flexible exosuit. In some examples, theelectroadhesive element 800 could be operated to enable a wearer of theflexible exosuit to climb a wall, cliff, or other surface by operatingthe electroadhesive element 800 to adhere to the wall, cliff, or othersurface while the wearer and/or exosuit transmitted a force through theelectroadhesive element 800 allowing the wearer and/or flexible exosuitto lift the wearer and flexible exosuit upwards.

FIG. 8A shows a front view of the electroadhesive element 800. Thenonconductive substrate 840 is substantially circular and planar, andthe first 810 and second 820 conductors are substantially parallelalternating bars. FIG. 8C illustrates an electroadhesive strap 850 thatis configured similarly to the electroadhesive element 800. Theelectroadhesive strap 850 includes a nonconductive substrate 880 intowhich are embedded parallel alternating first 860 and second 860conductors that are configures as strips. The electroadhesive strap 850additionally includes an insulator layer (not shown). Theelectroadhesive strap 850 could be operated similarly to theelectroadhesive element 800 and could be disposed on the surface of aflexible or rigid force-transmitting element of a flexible exosuit toenable the flexible or rigid force-transmitting element to adhere toskin of a wearer of the flexible exosuit and to transmit forces into theskin of the wearer.

Note that the electroadhesive element 800 and electroadhesive strap 850and operations and applications thereof described herein are meant asillustrative examples only. An electroadhesive element could be disposedas part of a flexible exosuit or as part of some other device or systemto enable electrically-controlled adhesion to objects or other devicesor systems. An electroadhesive element could take the form of a circle,a strap, or any other shape that could be substantially flat or couldhave a curved rigid or flexible surface according to an application.Further, the arrangement of first and second sets of conductors asparallel alternating strips on the surface of an electroadhesive elementis intended as an illustrative example. The strips could be circles,rectangles, spirals, polygons, or other shapes and they could be tiled,intercalated, or related to each other in some other manner according toan application. There could be more than two sets of conductors; indeed,each conductor of an electroadhesive element could be individuallyelectronically actuated. For example, high voltage could be appliedindividually to specified conductors of an electroadhesive element in aspecified region of the electroadhesive element to enable only thespecified region of the electroadhesive element to adhere to an object.Other operations and configurations are anticipated.

VI. Structures for Transmitting Forces Between a Flexible Exosuit Systemand a User.

A flexible exosuit can include actuators (e.g., exotendons, TSAs)capable of generating, transmitting, modulating, or otherwisecontrolling forces between two or more elements. In order to enableapplications of the flexible exosuit (e.g., applying forces and ortorques to a body of a wearer to assist, record, or otherwise interactwith physical activities of a wearer), the flexible exosuit can beconfigured to transmit forces into tissues of a wearer (e.g., bones,joints, and muscles of the wearer) by transmitting forces into the skinof the wearer. By transmitting forces into the tissues of the wearer,rather than transmitting forces across joints of the wearer using arigid exoskeleton, the flexible exosuit can be lighter and can causeless impediment to motions of the wearer (including motions of joints),even when unpowered, than a rigid exoskeleton. A flexible exosuit caninclude rigid and flexible elements to transmit forces from elements ofthe flexible exosuit (e.g., actuators) to other elements of the flexibleexosuit and/or the skin of a wearer. The flexible exosuit could includestraps, plates configured to follow a contour of a body part of thewearer, flexible meshes, boots, harnesses, or other flexible, rigid, andsemi-rigid elements.

Flexible and/or rigid elements of a flexible exosuit can be configuredto apply a normal force and/or stress evenly across a section of awearer's skin. Distributing loads evenly across a section of thewearer's skin can reduce discomfort experienced by the wearer whenforces are applied to the skin and can reduce the change of injury(e.g., tears or abrasions of the skin) of the wearer. To evenlydistribute a load applied to skin of the wearer, the flexible exosuitcould include a flexible mesh or woven network of flexible elementsconfigured to be mounted to the skin.

For example, the flexible exosuit could include a cuff made of wovenflexible straps that has a shape specified to conform to an aspect ofthe wearer's body, e.g., the thigh of the wearer. The cuff could includean attachment point for a force-transmitting actuator (e.g., anexotendon or a TSA) and the woven elements of the cuff could beconnected to the attachment point such that forces transmitted to thecuff from the actuator are in turn transmitted through the wovenelements and into the skin of the wearer evenly along the length of thewoven elements. The compliance of the woven elements, the pattern of thewoven structure, and other aspects of the configuration of the cuffcould be specified based on information about the aspect of the wearer'sbody (e.g., thigh). For example, the pattern of individual wovenelements of a cuff configured to be mounted to a shank of a limb of awearer could follow a catenary pattern as the individual woven elementwrapped around the shank of the limb. The shape of the catenary, patternof interconnection between individual woven elements, and compliance ofindividual woven elements could be specified to ensure that the normalforce between a segment of a woven element and the skin beneath thesegment was sufficient to enable the segment to transmit an amount ofshear force into the skin that was substantially similar to the amountof shear force transmitted into other areas of the skin beneathrespective other segments of the woven element. Other configurations offlexible and semi-flexible cuffs configured to be worn by a wearer andto transmit shear and/or normal forces into skin of the wearer areanticipated.

Flexible elements configured to transmit forces into skin of a wearercan be configured to follow, be adhered to, approximate, or otherwise berelated to lines of non-extension of the skin. Lines of non-extension ofthe skin are lines on the surface of the skin of a wearer along whichthe skin substantially does not deform during normal motions of thewearer and perpendicularly to which the skin substantially does deformduring normal motions of the wearer. A flexible strap (that is asubstantially linear element configured to be highly compliant indirections perpendicular to the length of the strap, and substantiallynon-compliant in along the length of the strap) could be adhered to skinalong a line of non-extension and the deformation of the skin inresponse to normal motions of the wearer could be substantiallyunaffected by the adhesion of the strap. Thus, the strap could be usedto transmit forces into the skin in a manner that did not substantiallyimpede normal motions of the wearer when the strap is not being used totransmit forces into the skin. Configuring flexible elements of aflexible exosuit to conform to lines of non-extension of skin couldreduce abrasion of the skin relative to the use of flexible elements notconfigure to substantially conform to and/or follow lines ofnon-extension of the skin.

Elements of a flexible exosuit (e.g., flexible and/or rigidforce-transmitting elements) could be adhered to skin of a wearer in avariety of ways. A chemical adhesive could be applied to bond elementsof the flexible exosuit to skin of the wearer and to prevent theelements from slipping. Elements of the flexible exosuit configured tocontact and/or transmit forces into skin of a wearer could includeelectroadhesive elements, and the electroadhesive elements could beconfigured to adhere the elements of the flexible exosuit to the skin.The electroadhesive elements could be operated to adhere to and releasefrom the skin according to an application. For example, theelectroadhesive elements could be operated to adhere elements of theflexible exosuit to the skin when actuators of the flexible exosuit werebeing operated to apply forces to the body of the wearer. Theelectroadhesive elements could be operated to release the elements ofthe flexible exosuit from the skin of the wearer at other times to saveenergy, to increase the comfort of the wearer, to allow forrepositioning of elements of the flexible exosuit, or to enable otherfunctions or applications.

A flexible exosuit that includes elements configured to transmit forcesinto skin over at least two segments of the body of a wearer (e.g., skinof the thigh and of the calf of the wearer) could include actuatorsconfigured to apply, modulate, or otherwise transmit forces between theat least two segments to effect and/or affect a torque on a joint orjoints between the at least two segments (e.g., to apply a torque to theknee of the wearer). Additionally or alternatively, such a flexibleexosuit could be configured to transfer a load or other forces betweensegments of the body to enable some application.

Flexible and/or rigid elements of a flexible exosuit that are configuredto transmit forces into skin of a wearer can be incorporated into, on,and/or beneath other elements of the flexible exosuit and/or othergarments worn by a wearer. In some examples, the flexible exosuitincludes a conformal undersuit. Flexible and/or rigid force-transmittingelements of the flexible exosuit can be incorporated into and/ordisposed on top of elements of the undersuit. In examples where theforce-transmitting elements are disposed on top of elements of theundersuit, the elements of the undersuit could be configured to enablethe transmission of normal and/or shear forces from theforce-transmitting elements into the skin. Additionally oralternatively, the undersuit could allow the force-transmitting elementsto move relative to the skin when the force-transmitting elements werenot transmitting substantial forces into the skin (e.g., to reduceabrasion and discomfort of the skin during motion of the wearer). Theundersuit could include electroadhesive elements or other elements tofacilitate and/or modulate the transmission of forces between flexibleand/or rigid force-transmitting elements of the flexible exosuit and theskin of the wearer.

The undersuit could be configured to provide additional functionality.The material of the undersuit could include anti-bacterial, anti-fungal,or other agents (e.g., silver nanoparticles) to prevent the growth ofmicroorganisms. The undersuit could be configured to manage thetransport of heat and/or moisture (e.g., sweat) from a wearer to improvethe comfort and efficiency of activity of the wearer. The undersuitcould include straps, seams, Velcro, or other elements configured tomaintain a specified relationship between elements of the flexibleexosuit and aspects of the wearer's anatomy. This could additionallyincrease the ease with which a wearer could don and/or doff the flexibleexosuit. The undersuit could additionally be configured to protect thewearer from ballistic weapons, sharp edges, shrapnel, or otherenvironmental hazards (by including, e.g., panels or flexible elementsincluding Kevlar or other armor materials).

VII. System Overview of an Exosuit System

FIG. 9 is a simplified block diagram illustrating the components of aflexible exosuit 900, according to an example embodiment. Exosuit 900may take the form of or be similar to flexible exosuit 100 shown inFIG. 1. However, exosuit 900 may also take other forms, such as anexosuit configured to be worn over only the legs, torso, arms, or acombination of these or other aspects of a wearer. The exosuit 900 couldinclude elements similar to other sensors, actuators, or other elementsdescribed herein (e.g., exotendons 200 a-d, TSAs 400, 500 a-g, 600 a-e,electroadhesive elements 800, 850, STEMs 1000 a-d) and/or could includeother elements according to an application. Further, the exosuit 900could consist of or include structures similar to the examplejoint-crossing and/or joint-torque-applying structures described herein(e.g., 1100 a-i, 1200). Exosuit 900 could also take the form of anexosuit configured to be used in combination with a prosthetic (e.g., anartificial limb). Exosuit 900 also could take other forms.

In particular, FIG. 9 shows an example of an exosuit 900 havingcontroller(s) 910, physiological sensors 920, kinematic sensors 930,environmental sensors 931, user interface(s) 970, battery(s) 911, andcommunications interface(s) 980. The exosuit 900 additionally includeshigh voltage driver(s) 955 configured to drive exotendon(s) 940 andhaptic elements(s) 950 of the exosuit 900. The exosuit 900 furtherincludes motor controller(s) 965 configured to control twisted stringactuator(s) 960 (TSA(s)) of the exosuit 900 using information from loadcell(s) 962 and encoders 964 that are configured to detect properties(e.g., applied load, rotation rate and direction) of elements of theTSA(s) 960.

The exosuit 900 additionally includes flexible and/or rigid elements(not shown) configured to be worn by a wearer of the exosuit 900 and toenable elements of the exosuit 900 to apply forces to the body of thewearer or to enable other functions of the exosuit 900 according to anapplication. The components of the exosuit 900 may be disposed on or inthe flexible and/or rigid wearable elements of the exosuit 900 or otherelements of the exosuit 900 (e.g., protective housings, a backpack orpouch) to enable functions of the exosuit. Note that exosuit 900 isintended as an example, and that exosuits as described herein can havemore or fewer components than those illustrated in FIG. 9. For example,an exosuit could lack TSAs, exotendons, and/or haptic elements, and/orcould include electroadhesive elements or other components.

The physiological sensors 920 include a temperature sensor 922, a heartrate sensor 924 (that could include an ECG sensor, an optical pulsesensor, a microphone, or some other elements configured to detect apulse of a wearer), and a Galvanic skin response (GSR) sensor 928. Thephysiological sensors 920 could include additional or alternate sensors.The kinematic sensors 930 include strain sensors 932, force sensors 934,EMG sensors 936, and inertial measurement unit (IMU) sensors 938. Thekinematic sensors 930 could include one or more of each of the types ofsensors according to an application of the flexible exosuit; forexample, the flexible exosuit could include and IMU 938 for each of thesegments of a wearer's body, such that the exosuit 900 could operate theIMUs 938 to determine a posture of the wearer's body that includesinformation about the relative location and orientation of each segmentof the wearer's body. The kinematic sensors 930 could include additionalor alternate sensors. The environmental sensors 931 include globalpositioning system (GPS) location receivers 933 configured to determinethe location of the exosuit 900 on the surface of the Earth using GPSsignals, light detection and ranging (LIDAR) sensors 935 configured todetect the location of objects in the environment of the exosuit 900,and humidity sensors 937. The environmental sensors 931 could includeadditional or alternate sensors.

The battery(s) 911 are configured to power elements of the exosuit 900.The battery(s) 911 could be rechargeable or single-use. The battery(s)911 could include a variety of chemistries, including but not limited toalkaline, zinc-air, zinc-oxide, nickel-cadmium, lead-acid,lithium-polymer, and nickel metal hydride. The battery(s) 911 couldinclude a single battery or a plurality of batteries disposed on orwithin the exosuit 900 according to an application. Additionally oralternatively, the exosuit 900 could be powered by a tether (e.g., atether plugged into a mains power grid), a fuel cell, a chemical engine(e.g., chemical engine that include an electro-active polymer asdescribe above), solar cells, or some other power source or combinationof power sources.

Controller(s) 910 may be a general-purpose processor(s), a specialpurpose processor(s) (e.g., digital signal processors, applicationspecific integrated circuits, etc.), or combinations thereof. The one ormore controllers 910 can be configured to execute computer-readableprograms that are stored in a computer readable medium disposed in theexosuit 900 (not shown) and that are executable to provide thefunctionality of the exosuit 900 described herein. Additionally oralternatively, the controller(s) 900 could execute instructions receivedfrom an outside system using the communications interface(s) 980. Theinstructions could include descriptions of application programminginterfaces (APIs) or other protocols to allow functions of the exosuit900 (e.g., biosensing, actuation) to be monitored, initiated, altered,or otherwise interacted with by a remote system communicating with theexosuit through some communications channel (e.g., a smartphoneapplication communicating with the exosuit 900 through thecommunications interface(s) 980).

Controller(s) 910 may be disposed at various locations in or on theexosuit 910 according to an application. For example, one of thecontroller(s) could be disposed in the motor controller(s) 965 tofacilitate high-bandwidth, low-latency control of the TSA(s) 960. Thecontroller(s) 910 could be configured in ways related to their locationand/or function in the exosuit 900. For example, a controller disposedin the motor controller(s) 965 could be an FPGA or ASIC while acontroller configured to coordinate all of the elements of the exosuit900 (i.e., 920, 930, 931, 955, 965, 970, 980) could be a moremulti-purpose processor (e.g., ARM, PIC, x86). Further, the programinstructions executed by individual controllers of the controller(s) 910could be specific to the individual controllers. For example, acontroller disposed to enable functions of the user interface(s) 970 mayexecute program instructions containing descriptions of the userinterface elements and methods for conveying information to/from othercontrollers, while a controller disposed to enable control of anactuator may execute program instructions that define a real-timeoperating system (RTOS) and PID controller that enable fixed-latencyupdates of any actuator control outputs generated by the controller.

The user interface(s) 970 could include buttons, screens, touchpads,indicator lights, joysticks, or other elements configured to presentinformation to a wearer of the exosuit 900 and/or to receive commandsfrom the wearer. The user interface(s) 970 could be operated to allowthe user to select a mode of operation of the exosuit 900, to adjust oneor more parameters of the exosuit 900, initiate a function of theexosuit 900, or to otherwise input information to the exosuit 900. Forexample, the user interface(s) 970 could include a touchscreen disposedon an element of the exosuit 900 configured to be worn on an arm of thewearer. The touchscreen could be operated to present a number ofoperating modes of and/or applications installed in the exosuit 900 tothe user (e.g., walk, sprint, stand at attention, jump, carry object,lift object), to detect the presence and location of the wearer's fingeron the touchscreen, to detect the operating mode and/or applicationselected by the wearer, and to communicate the identity of the selectedoption to another system (e.g., the controller(s) 910).

Conversely, the interface(s) 970 could be operated to indicateinformation to the user. For example, the interface(s) 970 could includea display screen (possibly a touchscreen additionally configured toaccept user input, as described above) configured to indicate a mode orproperty of the exosuit 900, a component of the exosuit 900, the wearerof the exosuit, or some other information. Example information indicatedby the screen could include a battery level of a battery powering theexosuit 900, a pulse rate of the wearer as detected by the physiologicalsensors 920, an operational mode of the exosuit 900, and the posture ofthe wearer of the exosuit 900 as detected by the physiological sensors920, environmental sensors 931, and/or kinematic sensors 930.

The communications interface(s) 980 could be any component or componentsconfigured to enable elements of the exosuit 900 (e.g., controller(s)910) to send and/or receive information to/from some other system orsystems. For example, the communications interface(s) 980 could includea radio transceiver configured to transmit telemetry data (e.g., exosuit900 operations, physiological data about a wearer) to a remote system.In another example, the communications interface(s) 980 could beconfigured to communicate with a cellphone or tablet of the wearer andto facilitate control of the exosuit 900 by an application on thecellphone or tablet by enabling communication between the applicationand the controller(s) 910. The communications interface(s) 980 could beconfigured to communicate over wired and/or wireless media. Thecommunications interface(s) 980 could include radios, Bluetoothtransceivers, WiFi transceivers, LTE or other cellular communicationsequipment, satellite uplinks, ZigBee transceivers, IRdA or other opticalcommunications elements, or some other components configured to enablecommunications between elements of the exosuit 900 (e.g., controller(s)910) and some remote system.

The communications interface(s) 980 could be operated to enable thesending of telemetry about the exosuit 900 and/or wearer, the sendingand/or receiving of calibration data for elements of the exosuit 900 oraspects of a wearer, receiving program instructions or other data from aremote system (e.g., an online application store). Further, thecommunications interface(s) 980 could be configured to facilitatecommunication between a wearer of the exosuit 900 and some other personor system. For example, the exosuit 900 could include a microphoneand/or speakers and could operate the communications interface(s) 980,microphone, and speakers to facilitate verbal communications between thewearer and another person.

The high-voltage driver(s) 955 are configured to produce and modulatehigh voltage signals to operate exotendon(s) 940 and/or electropolymerartificial muscle (EPAM) haptic element(s) 950. The high-voltagedriver(s) 955 could include inductors, transformers, flybacks,capacitors, high-voltage switches, oscillators, or other elements toenable the production, storage, modulation, gating, and other functionsrelating to high voltage. The high voltage could be a voltage of severalhundred volts, or some other voltage, according to the configuration ofthe exotendon(s) 940 and/or haptic element(s) 950. In some examples, thehigh-voltage driver(s) 955 could include a single high voltage generatorand one or more high-voltage switches configured to gate a high voltagegenerated by the high voltage generator to a set of respective actuators(e.g., exotendon(s) 940, haptic element(s) 950). The high-voltagedriver(s) 955 could be configured to provide intermediate levels ofvoltage to an actuator (e.g., exotendon(s) 940, haptic element(s) 950)to enable operation of the actuator at an intermediate level, e.g., tooperate an exotendon 940 such that the exotendon 940 slipped undertension rather than being fully clutched (no slip) or fully un-clutched(free movement).

The high-voltage driver(s) 955 could be configured to enable otherfunctions. In some examples, the high-voltage driver(s) 955 could beconfigured to allow for detection of some property or properties of theactuator(s) 940, 950. For example, the high-voltage driver(s) 955 couldbe configured to detect a capacitance of an exotendon 940 and thedetected capacitance could be used to determine a length, strain, orother information about the exotendon 940. Further, the high-voltagedriver(s) 955 could be configured to perform closed-loop control of anactuator; for example, the high-voltage driver(s) 955 could detect alength of an exotendon 940 that is under tension and could operate toapply a voltage to the exotendon 940 such that the length of theexotendon 940 increased at a controlled rate, or according to some othercommand or constraint. In some examples, the high-voltage driver(s) 955could be configured to ensure safe operation, e.g., to preventover-voltage, over-current, injury to a wearer, damage to elements ofthe exosuit 900 or some other adverse condition by including breakers,varistors, voltage clamping diodes, or some other element or elements.The high-voltage driver(s) 955 could additionally include level-shiftingcircuitry to enable components operating at lower voltages (e.g.,controller(s) 910) to operate the high-voltage driver(s) 955 withoutbeing damaged by the high voltages produced in the high-voltagedriver(s) 955.

The motor controller(s) 965 are configured to produce and modulatevoltages and/or currents to operate motor(s) of TSA(s) 960. The motorcontroller(s) 965 could include inductors, transformers, flybacks, buckconverters, boost converters, capacitors, switches, oscillators,controllers, comparators, or other elements to enable the production,storage, modulation, gating, and other functions relating to driving amotor. The motor controller(s) 965 could be configured to producevoltage and/or current waveforms to drive coils of motors of TSA(s) 960.For example, the motor controller(s) 965 could includepulse-width-modulated (PWM) switches configured to produce pulses ofvoltage having specified pulse widths such that a coil of a motorconnected to such a PWM switch would experience an effective currentrelated to the specified pulse widths. The motor controller(s) 965 couldinclude electronics (e.g., comparators, ADCs, amplifiers) to detectrotation of and/or forces applied to elements of the TSA 960 using theencoder(s) 964 and/or load cell(s) 962, respectively. The motorcontroller(s) 965 could control the timing of voltages and/or currentsapplied to motor coils based on a detected angle of the rotor of themotor and/or a magnetic field detected by a Hall sensor disposed in themotor. Additionally or alternatively, the motor controller(s) 965 couldcontrol the timing of voltages and/or currents applied to motor coilsbased on a detected back-EMF from the motor coils and/or currentsthrough motor coils detected using current sensors of the motorcontroller(s) 965. Further, the motor controller(s) 965 could beconfigured to perform closed-loop control of TSA(s) 960; for example,the motor controller(s) 965 could detect a tension being applied by aTSA 960 (e.g., by using the load cell(s) 962) and could operate the TSA960 such that the tension increased/decreased at a controlled rate, oraccording to some other command or constraint.

VIII. Smart Tendon Exomuscles

Exotendons, twisted string actuators (TSAs), and other actuators can beoperated to apply and/or transmit forces individually between twodifferent actuated elements. Exotendons, TSAs, and other actuators canalternatively be incorporated into composite actuators to apply and/ortransmit forces between two different actuated elements. Compositeactuators including exotendons and TSAs could be configured to operatein a manner that was superior in some way to operating those actuatorsindividually. For example, a composite actuator could have a superiorcompliance, similarity to biological actuators, efficiency, range ofmotion, stroke length, or some other property when compared toindependently configured and/or operated exotendons and/or TSAs. Acomposite actuator including at least one TSA and at least one exotendonis referred to herein as a smart tendon exomuscle (STEM).

FIG. 10A illustrates a STEM 1000 a attached to first 1010 a and second1020 a actuated elements such that the STEM 1000 a could be operated toapply a force and/or change a displacement between the first 1010 a andsecond 1020 a actuated elements. The STEM 1000 a includes a motor 1030 arigidly coupled to the first actuated element 1010 a. A first end of atwisted string 1035 a is mechanically coupled to a first end of anexotendon 1040 a. A second end of the exotendon 1040 a is mechanicallycoupled to the second actuated element 1020 a. A rotor of the motor 1010a is coupled to a second end of the twisted string 1035 a such that themotor 1010 a can be operated to apply a torque and/or rotation to thesecond end of the twisted string 1035 a such that a force and/or changein displacement is applied between the first 1010 a actuated element andthe first end of the exotendon 1040 a. The exotendon 1040 a isconfigured to act as a switched compliance element, able to beelectrically operated to have one of at least two effective compliances(i.e., two different relationships between forces applied between thefirst and second ends of the exotendon 1040 a and strains of theexotendon 1040 a). The exotendon 1040 a and twisted string actuator 1030a, 1035 a could be configured similarly to other exotendons (e.g., 200a, 200 b, 200 c, 200 d) and TSAs (e.g., 400, 500 a-g, 600 a-e),respectively, described herein or could be configured in other ways.

The exotendon 1040 a could be configured such that it had a very highcompliance when unclutched and a very low compliance when clutched. Thatis, the exotendon 1040 a could be configured such that it acted toengage and disengage the TSA 1030 a, 1035 a from the first 1010 a andsecond 1020 a actuated elements. The exotendon 1040 a could be operatedin this way to allow a range of motion of the TSA 1030 a, 1035 a to beadapted to an application. The range of motion of the TSA 1030 a, 1035 ais the total change in displacement between the first 1010 a and second1020 a actuated elements that the TSA 1030 a, 1035 a could effect byrotating the second end of the twisted string 1035 a.

In some examples, the STEM 1000 a could be part of a flexible exosuit,and the first 1010 a and second 1020 a actuated elements could be ashank of a wearer's leg and a wearer's foot, respectively, such that theSTEM could be operated to apply a torque to the ankle of the wearer.Displacement of the first 1010 a and second 1020 a actuated elements cancorrespond to changes in angle of the ankle of the wearer. Thedisplacement corresponding to the full range of ankle angles that thewearer could experience could be greater than the range of motion of theTSA 1030 a, 1035 a. In such a situation, the exotendon 1040 a could beoperated to un-clutch the TSA 1030 a, 1035 a to allow the wearer tofreely move their ankle joint. Once it was determined that the flexibleexosuit should apply a torque to the ankle of the wearer, the exotendon1040 a could be operated to clutch the TSA 1030 a, 1035 a and the TSA1030 a, 1035 a could be operated to apply the torque to the ankle of thewearer. In this way, incorporation into the STEM 1000 a could be said tohave increased the effective range of motion of the TSA 1030 a, 1035 aby allowing the first 1010 a and second 1020 a actuated elements to beun-clutched from the TSA 1030 a, 1035 a and repositioned.

In some examples, the exotendon 1040 a could be clutched (i.e., could beoperated to have a relatively low compliance). A flexible exosuit thatincludes the STEM 1000 a could operate the TSA 1030 a, 1035 a andsensors (e.g., load cell(s), encoder(s), accelerometer(s)) according tosome application. The flexible exosuit could operate the TSA 1030 a,1035 a and sensors to determine an optimal transmission ratio, length,stroke length, or other property or properties of the TSA 1030 a, 1035 arelative to the application. The flexible exosuit could then clutch andun-clutch the exotendon 1040 a to adjust the transmission ratio, length,stroke length, or other property or properties of the TSA 1030 a, 1035 ato correspond to the determined optimal property or properties of theTSA 1030 a, 1035 a.

For example, the transmission ratio of a TSA included in a STEMconfigured to apply forces across an ankle of a wearer could be relatedto the weight, geometry, or other properties of the wearer and/or of theSTEM. A flexible exosuit including the STEM could operate the STEM toapply forces to the ankle of the wearer, determine the optimaltransmission ratio of the TSA, and operate STEM to cause thetransmission ratio of the TSA to correspond to the determined optimaltransmission ratio. Thus could include un-clutching the exotendon, thenoperating the motor of the STEM to change the twist of the twistedstring of the STEM (thus changing the transmission ration of the TSA),and then clutching the exotendon. In some examples, the flexible exosuitcould indicate to a wearer (using a user interface, a haptic element,operation of the STEM, or some other method) actions to be performed bythe wearer to facilitate a change in the properties of the TSA (e.g., byinstructing the wearer to exert an isometric force while the exotendonis un-clutched so that the TSA can be operated to change a property ofthe TSA; the exotendon could subsequently clutch such that the TSA couldassist the musculature of the wearer in applying dynamic and/or staticforces).

The STEM 1000 a could additionally or alternatively be operated in abio-mimetic manner. That is, the compliance of the exotendon 1040 a andthe force and/or displacement of the TSA 1010 a, 1015 a could becontrolled to enable application and/or transmission of forces betweenthe first 1010 a and second 1020 a actuated elements that was moreefficient, less likely to cause injury or damage to a wearer or systemattached to the first 1010 a and second 1020 a actuated elements, or insome other way superior to operating individual TSAs and/or exotendonsaccording to an application. In some examples, the exotendon 1040 acould be configured to extract, inject, and/or store mechanical energyby including one or more springs or other compliant elements. In anexample, the STEM 1000 a could operate such an exotendon 1040 a to be‘charged’ with elastic potential energy by operating the TSA 1010 a,1015 a to apply a force and displacement to the exotendon 1040 a. Theexotendon 1040 a could then be operated to release the stored elasticpotential energy. For example, the exotendon 1040 a could be operated torelease the stored elastic potential energy to allow a wearer of aflexible exosuit containing the STEM 1000 a to accomplish a jump thatwas higher than the wearer and/or TSA 1010 a, 1015 a could haveaccomplished without the elastic potential energy stored in theexotendon 1040 a.

A STEM configured similarly to STEM 1000 a could be configured as aself-contained, flexible unit. FIG. 10B illustrates a STEM 1000 battached to first 1010 b and second 1020 b actuated elements such thatthe STEM 1000 b could be operated to apply a force and/or change adisplacement between the first 1010 b and second 1020 b actuatedelements. The STEM 1000 b includes a motor 1030 b rigidly coupled to afirst end of a flexible transmission tube 1035 b that is configured totransmit torques and/or forces along its length and to be flexible indirections perpendicular to its length (similar to the outer housing ofa Bowden cable). A second end of the flexible transmission tube 1035 bis rigidly coupled to the first actuated element 1010 b. A first end ofa twisted string 1037 b is mechanically coupled to a first end of anexotendon 1040 b. A second end of the exotendon 1040 b is mechanicallycoupled to the second actuated element 1020 b. The twisted string 1037 bis partially contained within and protected by flexible transmissiontube 1035 b. A rotor of the motor 1010 b is coupled to a second end ofthe twisted string 1037 b such that the motor 1010 b can be operated toapply a torque and/or rotation to the second end of the twisted string1037 b such that a force and/or change in displacement is appliedbetween the first 1010 b actuated element and the first end of theexotendon 1040 b. The exotendon 1040 b is configured to act as aswitched compliance element, able to be electrically operated to haveone of at least two effective compliances (i.e., to have two differentrelationships between forces applied between the first and second endsof the exotendon 1040 b and strains of the exotendon 1040 b). Theexotendon and twisted string actuator 1030 b, 1035 b could be configuredsimilarly to other exotendons (e.g., 200 a, 200 b, 200 c, 200 d) andTSAs (e.g., 400, 500 a-g, 600 a-e), respectively, described herein orcould be configured in other ways. STEM 1000 b could be operatedsimilarly to STEM 1000 a.

FIG. 10C illustrates a STEM 1000 c attached to first 1010 c and second1020 c actuated elements such that the STEM 1000 c could be operated toapply a force and/or change a displacement between the first 1010 c andsecond 1020 c actuated elements. The STEM 1000 c includes a motor 1030 crigidly coupled to the first actuated element 1010 c. A first end of atwisted string 1035 c is mechanically coupled to a first end of anexotendon 1040 c. A second end of the exotendon 1040 c is mechanicallycoupled to the first actuated element 1010 c. The exotendon 1040 c isflexible and wrapped around a bar 1025 c that is rigidly coupled to thesecond actuated element 1020 c. A rotor of the motor 1010 c is coupledto a second end of the twisted string 1035 c such that the motor 1010 ccan be operated to apply a torque and/or rotation to the second end ofthe twisted string 1035 c such that a force and/or change indisplacement is applied between the first 1010 c actuated element andthe first end of the exotendon 1040 c. The exotendon 1040 c isconfigured to act as a switched compliance element, able to beelectrically operated to have one of at least two effective compliances(i.e., two different relationships between forces applied between thefirst and second ends of the exotendon 1040 c and strains of theexotendon 1040 c). The exotendon 1040 c and twisted string actuator 1030c, 1035 c could be configured similarly to other exotendons (e.g., 200a, 200 b, 200 c, 200 d) and TSAs (e.g., 400, 500 a-g, 600 a-e),respectively, described herein or could be configured in other ways.STEM 1000 c could be operated similarly to STEM 1000 c.

FIG. 10D illustrates a STEM 1000 d attached to first 1010 d and second1020 d actuated elements such that the STEM 1000 d could be operated toapply a force and/or change a displacement between the first 1010 d andsecond 1020 d actuated elements. The STEM 1000 d includes a motor 1030 drigidly coupled to the first actuated element 1010 d. A first end of atwisted string 1035 d is mechanically coupled to a first end of a firstexotendon 1040 d. A second end of the first exotendon 1040 d ismechanically coupled to the second actuated element 1020 d. A rotor ofthe motor 1010 d is coupled to a second end of the twisted string 1035 dsuch that the motor 1010 d can be operated to apply a torque and/orrotation to the second end of the twisted string 1035 d such that aforce and/or change in displacement is applied between the first 1010 dactuated element and the first end of the first exotendon 1040 d. TheSTEM 1000 d additionally includes a second exotendon 1045 d that has twoends that are rigidly coupled to the first 1010 d and second 1020 dactuated elements, respectively. The exotendons 1040 d, 1045 d areconfigured to act as a switched compliance elements, able to beindependently electrically operated to each have one of at least twoeffective compliances (i.e., two different relationships between forcesapplied between first and second ends of an exotendon 1040 d, 1045 d andstrains of the exotendon 1040 d, 1045 d). The exotendons 1040 d, 1045 dand twisted string actuator 1030 d, 1035 d could be configured similarlyto other exotendons (e.g., 200 a, 200 b, 200 c, 200 d) and TSAs (e.g.,400, 500 a-g, 600 a-e), respectively, described herein or could beconfigured in other ways.

The STEM 1000 d could be operated to provide some application oroperation of a flexible exosuit. In some examples, the second exotendon1045 d could be connected in series with a spring to allow the spring tobe clutched to transmit forces (e.g., to/from a body of a wearer) duringa first period of time and to transmit substantially no forces during asecond period of time. For example, the exotendon 1045 d could beconnected in series with a spring and the first 1010 d and second 1020 dactuated elements could be the calf and the foot of a wearer, such thatthe STEM 1000 d could be operated to apply an extensor torque to theankle of the wearer. The second exotendon 1045 d could be clutchedfollowing contact of the heel of the user with the ground duringlocomotion. The clutched spring could then be ‘charged’ with elasticpotential energy as the user flexes their ankle. The ‘stored’ elasticpotential energy could be released to the ankle of the wearer as thewearer extends their ankle before lifting their foot from the ground;this storage and release of mechanical energy from/to the ankle of thewearer could increase the efficiency of the locomotion of the wearer.The second exotendon 1045 d could be un-clutched following the liftingof the wearer's foot from the ground, such that the second exotendon1045 d and spring did not substantially affect the rotation and/ortorque at the wearer's ankle while the wearer's foot was not in contactwith the ground. In parallel, the first exotendon 1040 d could beclutched at the point in time that the spring began to release storedelastic potential energy, and un-clutched following the lifting of thewearer's foot from the ground. While the first exotendon 1040 d isclutched, the TSA 1030 d, 1035 d could be operated to apply an extensortorque to the ankle of the wearer, assisting the spring and the musclesof the wearer in applying force against the ground through the foot ofthe wearer. Other configurations and patterns of use of the STEM 1000 dare anticipated according to an application. Further, a spring connectedin series with an exotendon could be implemented as an element of theexotendon.

In some examples, the exotendons 1040 d, 1045 d and/or additionalexotendons (not shown) included in the STEM 1000 d could be clutched andun-clutched in an alternating fashion to allow greater forces to begenerated and/or applied between the first 1010 d and second 1020 dactuated elements. For example, the exotendons 1040 d, 1045 d could beoperated to ‘ratchet’ a spring, mechanically connecting it toforce-applying and/or force generating elements (the body of a wearer,the TSA 1030 d, 1035 d) to progressively add mechanically energy in aspring (not shown and/or included in the exotendons 1040 d, 1045 d).Other repeated, mechanically additive operations of a STEM areanticipated.

Note that the STEMs described herein (e.g., 1000 a, 1000 b, 1000 c, 1000d) are intended as non-limiting illustrative examples. Otherconfigurations and operations of a STEM are anticipated. Further, theTSA of any example STEM herein could be replaced with some other linearactuator, for example, an EPAM.

IX. Configurations of Elements of a Flexible Exosuit to Apply Forcesand/or Torques to a Single Joint

Configurations of actuators and rigid and flexible force-transmittingelements in a flexible exosuit can enable the transmission of forcesfrom a first segment of a wearer's body to a second segment. This can beaccomplished using electrically-operated elements such that the flexibleexosuit could operate the actuators to minimally encumber relativemotion of the first and second segments. FIGS. 11A-11I illustrateschematic side views, respectively of flexible exosuits 1100 a-iconfigured to selectively transmit forces between the calf and the footof respective wearers 1105 a-I such that torques are applied torespective ankles 1107 a-i.

FIG. 11A illustrates elements of a flexible exosuit 1100 a configured toapply an extensor torque to the ankle 1107 a of a wearer 1105 a and/or atensile force between the calf and the foot of the wearer 1105 a. Theflexible exosuit 1100 a includes a motor 1110 a rigidly coupled to afirst force-transmitting element (FTE) 1130 a. The firstforce-transmitting element 1130 a is configured to couple the motor 1110a to the calf of the wearer 1105 a such that the location of the motor1110 a relative to the calf of the wearer 1105 a does not significantlychange when the flexible exosuit 1100 a is operated to apply an extensortorque and/or tensile force to the body of the wearer 1105 a. Further,the first FTE 1130 a is configured such that the location of the motor1110 a relative to the calf of the wearer 1105 a is behind the calf ofthe wearer 1105 a. The flexible exosuit 1100 a additionally includes asecond FTE 1120 a configured to couple a first end of a twisted string1112 a to the foot of the wearer 1105 a. A second end of the twistedstring 1112 a is coupled to a rotor of the motor 1110 a.

Operation of the motor 1110 a causes an extensor torque to be applied tothe ankle of the wearer 1105 a. Operation of flexible exosuit 1100 a toapply such an extensor torque can also result in a normal force appliedto the posterior of the calf of the wearer 1105 a applied by straps 1132a coupled to the first FTE 1130 a and configured to maintain thelocation of the first FTE 1130 a relative to the calf of the wearer 1105a. Operation of flexible exosuit 1100 a to apply such an extensor torquecan further result in significant compressive loading of the ankle 1107a.

FIG. 11B illustrates elements of a flexible exosuit 1100 b configured toapply an extensor torque to the ankle 1107 a of a wearer 1105 b and/or atensile force between the calf and the foot of the wearer 1105 b. Theflexible exosuit 1100 b includes a motor 1110 b rigidly coupled to afirst FTE 1130 b. The first force-transmitting element 1130 b isconfigured to couple the motor 1110 b to the calf of the wearer 1105 bsuch that the location of the motor 1110 b relative to the calf of thewearer 1105 a does not significantly change when the flexible exosuit1100 b is operated to apply an extensor torque and/or tensile force tothe body of the wearer 1105 b. Further, the first FTE 1130 b isconfigured such that the location of the motor 1110 b relative to thecalf of the wearer 1105 b is in front of the calf of the wearer 1105 b.The flexible exosuit 1100 b additionally includes a second FTE 1120 bconfigured to couple a first end of a twisted string 1112 b to the footof the wearer 1105 b. A second end of the twisted string 1112 b iscoupled to a rotor of the motor 1110 b.

Operation of the motor 1110 b causes an extensor torque to be applied tothe ankle of the wearer 1105 b. Operation of flexible exosuit 1100 b toapply such an extensor torque can also result in a significant downwardshear force to be applied to the front of the calf of the wearer 1105 bby the first FTE 1130 b. Operation of flexible exosuit 1100 b to applysuch an extensor torque can further result in significant compressiveloading of the ankle 1107 b.

FIG. 11C illustrates elements of a flexible exosuit 1100 c configured toapply an extensor torque to the ankle 1107 c of a wearer 1105 c. Theflexible exosuit 1100 c includes a motor 1110 c rigidly coupled to afirst FTE 1130 c. The first force-transmitting element 1130 c isconfigured to couple the motor 1110 c to the calf of the wearer 1105 csuch that the location of the motor 1110 c relative to the calf of thewearer 1105 c does not significantly change when the flexible exosuit1100 c is operated to apply an extensor torque and/or tensile force tothe body of the wearer 1105 c. Further, the first FTE 1130 c isconfigured such that the location of the motor 1110 c relative to thecalf of the wearer 1105 c is in front of the calf of the wearer 1105 c.The flexible exosuit 1100 c additionally includes a second FTE 1120 cconfigured to couple a first end of a twisted string 1112 c to the footof the wearer 1105 c. The second FTE 1120 c includes at least one rigidmember (i.e., a member capable of transmitting compressive forces andtorques in addition to tensile forces) that extends from the heel of thewearer 1105 c to the first end of a twisted string 1112 c. A second endof the twisted string 1112 c is coupled to a rotor of the motor 1110 c.

Operation of the motor 1110 c causes an extensor torque to be applied tothe ankle of the wearer 1105 c. Operation of flexible exosuit 1100 c toapply such an extensor torque can result in the application of verylittle shear force between the front of the calf of the wearer 1105 cand the first FTE 1130 c. The movement of the rigid member of the secondFTE 1120 c can require a significant volume behind the calf of thewearer 1105 c to be clear of other objects.

FIG. 11D illustrates elements of a flexible exosuit 1100 d configured toapply an extensor torque to the ankle 1107 d of a wearer 1105 d and/or aforce between the calf and the foot of the wearer 1105 d. The flexibleexosuit 1100 d includes a motor 1110 d rigidly coupled to a first FTE1130 d. The first force-transmitting element 1130 d is configured tocouple forces to the calf of the wearer 1105 d. The flexible exosuit1100 d additionally includes first 1140 d, second 1150 d, and third 1160d rigid force-transmitting elements (RFTEs). The first RFTE 1140 d isconnected to the first FTE 1130 d and the second RFTE 1150 d throughbearings 1132 d and 1142 d, respectively. Third RFTE 1160 d is connectedto the second RFTE 1150 d and a second FTE 1120 d through bearings 1152d and 1162 d, respectively. Second FTE 1120 d is configured to coupleforces from bearing 1162 d to the foot of the wearer 1105 b. Theflexible exosuit 1100 d additionally includes a flexible transmissiontube 1114 d that is configured to transmit torques and/or forces alongits length and to be flexible in directions perpendicular to its length(similar to the outer housing of a Bowden cable). The ends of theflexible transmission tube 1114 d are connected to the motor 1110 d andto the second RFTE 1150 d. A twisted string 1112 d is partially disposedwithin the flexible transmission tube 1114 d and is connected to a rotorof the motor 1110 b and to the third RFTE 1160 d.

Operation of the motor 1110 d causes a force to be applied between theposterior ends of the second 1150 d and third 1160 d RFTEs, such thatbearings 1142 d and 1162 d are forced away from each other. This canresult in an extensor torque being applied to the ankle of the wearer1105 d. Operation of flexible exosuit 1100 d to apply such an extensortorque can also result in a significant upward shear force to be appliedto the front of the calf of the wearer 1105 d by the first FTE 1130 d.Operation of flexible exosuit 1100 d to apply such an extensor torquecan further result in a decreased compressive loading of the ankle 1107d.

FIG. 11E illustrates elements of a flexible exosuit 1100 e configured toapply an extensor torque to the ankle 1107 e of a wearer 1105 e and/or aforce between the calf and the foot of the wearer 1105 e. The flexibleexosuit 1100 e includes a motor 1110 e rigidly coupled to a first FTE1130 e. The first force-transmitting element 1130 e is configured tocouple forces to the calf of the wearer 1105 e. The flexible exosuit1100 e additionally includes first 1140 e and second 1150 e rigidforce-transmitting elements (RFTEs). The first RFTE 1140 e is connectedto the first FTE 1130 e and the second RFTE 1150 e through bearings 1132e and 1142 e, respectively. The second RFTE 1150 e is connected to asecond FTE 1120 e through a bearing 1152 e. Second FTE 1120 e isconfigured to couple forces from bearing 1152 e to the foot of thewearer 1105 e. The flexible exosuit 1100 e additionally includes atwisted string 1112 e that is connected to a rotor of the motor 1110 eand to the first RFTE 1140 e.

Operation of the motor 1110 e causes a force to be applied such thatbearings 1132 e and 1152 e are forced away from each other. This canresult in an extensor torque being applied to the ankle of the wearer1105 e. Operation of flexible exosuit 1100 e to apply such an extensortorque can also result in a significant upward shear force to be appliedto the front of the calf of the wearer 1105 e by the first FTE 1130 e.Operation of flexible exosuit 1100 e to apply such an extensor torquecan further result in a decreased compressive loading of the ankle 1107e.

FIG. 11F illustrates elements of a flexible exosuit 1100 f configured toapply an extensor torque to the ankle 1107 f of a wearer 1105 f and/or aforce between the calf and the foot of the wearer 1105 f. The flexibleexosuit 1100 f includes an actuator 1110 f rigidly coupled to a firstFTE 1130 f. The first force-transmitting element 1130 f is configured tocouple the actuator 1110 f to the calf of the wearer 1105 f such thatthe location of the actuator 1110 f relative to the calf of the wearer1105 f does not significantly change when the flexible exosuit 1100 f isoperated to apply an extensor torque and/or force to the body of thewearer 1105 f. Further, the first FTE 1130 f is configured such that thelocation of the actuator 1110 f relative to the calf of the wearer 1105f is in front of the calf of the wearer 1105 f. The flexible exosuit1100 f additionally includes a second FTE 1120 f configured to couple afirst end of a rigid force-transmitting element 1140 f (RFTE) through abearing 1142 f to the foot of the wearer 1105 f. The RFTE 1140 f isconfigured to be acted upon by the actuator 1110 f.

Operation of the actuator 1110 f causes a force to be applied such thatbearing 1142 f and first FTE 1130 f are forced away from each other.This can result in an extensor torque being applied to the ankle of thewearer 1105 f. Operation of flexible exosuit 1100 f to apply such anextensor torque can also result in a significant upward shear force tobe applied to the front of the calf of the wearer 1105 f by the firstFTE 1130 f. Operation of flexible exosuit 1100 f to apply such anextensor torque can further result in a decreased compressive loading ofthe ankle 1107 f. The actuator 1110 f and RFTE 1140 f could beconfigured to act as a rack-and-pinion, ball screw, and/or a screw drive(i.e., part of the RFTE 1140 f was threaded, knurled, or otherwisetoothed such that the actuator 1110 f could apply a downward forceand/or displacement to the RFTE 1140 f relative to the first FTE 1130f). Additionally or alternatively, the actuator 1110 f could be atwisted string actuator, and a twisted string of the actuator 1110 fcould extend from the actuator 1110 f to an end of the RFTE 1140 fopposite the bearing 1142 f such that operation of the twisted stringactuator 1110 f caused a downward force and/or displacement to beapplied to the RFTE 1140 f relative to the first FTE 1130 f. Otherconfigurations are anticipated.

FIG. 11G illustrates elements of a flexible exosuit 1100 g configured toapply an extensor torque to the ankle 1107 g of a wearer 1105 g. Theflexible exosuit 1100 g includes a motor 1110 g rigidly coupled to afirst FTE 1130 g. The first force-transmitting element 1130 g isconfigured to couple forces to the calf of the wearer 1105 g. Theflexible exosuit 1100 g additionally includes first 1140 g and second1150 g rigid force-transmitting elements (RFTEs). The first RFTE 1140 gis connected to the first FTE 1130 g and the second RFTE 1150 g throughbearings 1132 g and 1142 g, respectively. The second RFTE 1150 g isconnected to the anterior of a second FTE 1120 g through a bearing 1152g. Second FTE 1120 g is configured to couple forces to the foot of thewearer 1105 g from bearing 1152 g and from a first twisted string 1112 gthat is connected to the posterior of the second FTE 1120 g. The firsttwisted string 1112 g is additionally connected to elements of the motor1110 g such that the motor can be operated to rotate one end of thefirst twisted string 1112 g. The flexible exosuit 1100 g additionallyincludes a second twisted string 1114 g that is connected to the firstRFTE 1140 g and to elements of the motor 1110 g such that the motor 1110g can be operated to rotate one end of the second twisted string 1114 g.

Operation of the motor 1110 g causes a force to be applied such thatbearings 1132 g and 1152 g are forced away from each other and such thatthe posterior of the second FTE 1120 g is forced upward toward the motor1110 g. This can result in an extensor torque being applied to the ankleof the wearer 1105 g. The flexible exosuit 1100 g can be configured suchthat operation of the flexible exosuit 1100 g to apply such an extensortorque results in significantly no shear force between the front of thecalf of the wearer 1105 g and the first FTE 1130 g. Operation offlexible exosuit 1100 g to apply such an extensor torque can furtherresult in a normal force applied to the posterior of the calf of thewearer 1105 g applied by straps 1132 g coupled to the first FTE 1130 gand configured to maintain the location of the first FTE 1130 g relativeto the calf of the wearer 1105 g. Note that the flexible exosuit 1100 gbeing configured to drive the first 1112 g and second 1114 g twistedstrings using the motor 1110 g could be implemented in a number of ways,including a set of gears wherein the gears are configured to be drivenby the motor 1110 g and wherein two of the gear are configured to driverespective twisted strings 1112 g, 1114 g. Additionally oralternatively, the flexible exosuit 1100 g could include two motorsconfigured to drive respective twisted strings 1112 g, 1114 g.

FIG. 11H illustrates elements of a flexible exosuit 1100 h configured toapply an extensor torque to the ankle 1107 h of a wearer 1105 h. Theflexible exosuit 1100 h includes a motor 1110 h rigidly coupled to afirst FTE 1130 h. The first force-transmitting element 1130 h isconfigured to couple forces to the calf of the wearer 1105 h. Theflexible exosuit 1100 h additionally includes first 1140 h and second1150 h rigid force-transmitting elements (RFTEs). The first RFTE 1140 his connected to the first FTE 1130 h and the second RFTE 1150 h throughbearings 1132 h and 1142 h, respectively. The second RFTE 1150 h isconnected to the anterior of a second FTE 1120 h through a bearing 1152h. Second FTE 1120 h is configured to couple forces to the foot of thewearer 1105 h from bearing 1152 h and from a first twisted string 1112 hthat is connected to the posterior of the second FTE 1120 h. The firsttwisted string 1112 h is additionally connected to elements of the motor1110 h such that the motor can be operated to rotate one end of thefirst twisted string 1112 h. The first twisted string 1112 h isadditionally configured to slide over a pulley 1134 h that is connectedto the first FTE 1130 h. The flexible exosuit 1100 h additionallyincludes a second twisted string 1114 h that is connected to theposterior of the first RFTE 1140 h and to elements of the motor 1110 hsuch that the motor 1110 h can be operated to rotate one end of thesecond twisted string 1114 g.

Operation of the motor 1110 g causes a force to be applied such thatbearings 1132 h and 1152 h are forced away from each other and such thatthe posterior of the second FTE 1120 h is forced upward toward thepulley 1134 h. This can result in an extensor torque being applied tothe ankle of the wearer 1105 h. The flexible exosuit 1100 h can beconfigured such that operation of the flexible exosuit 1100 h to applysuch an extensor torque results in significantly no shear force betweenthe front of the calf of the wearer 1105 h and the first FTE 1130 h.Operation of flexible exosuit 1100 h to apply such an extensor torquecan further result in a normal force applied to the posterior of thecalf of the wearer 1105 g applied by straps coupled to the first FTE1130 h and configured to maintain the location of the first FTE 1130 hrelative to the calf of the wearer 1105 h. Note that the flexibleexosuit 1100 h being configured to drive the first 1112 h and second1114 h twisted strings using the motor 1110 h could be implemented in anumber of ways, including a set of gears wherein the gears areconfigured to be driven by the motor 1110 h and wherein two of the gearare configured to drive respective twisted strings 1112 h, 1114 h.Additionally or alternatively, the flexible exosuit 1100 h could includetwo motors configured to drive respective twisted strings 1112 h, 1114h.

The flexible exosuit 1100 h additionally includes a first exotendon 1162h connected between the first FTE 1130 h and the anterior of the secondFTE 1120 h and a second exotendon 1164 h connected between the posteriorend of the first RFTE 1140 h and the posterior end of the second FTE1120 h. The first and second exotendons 1162 h, 1164 h could be operatedto clutch and un-clutch elements having a specified compliance (e.g.,springs, straps) included in the exotendons 1162 i, 1164 i to store andrelease elastic potential energy and/or to modulate the impedance ofelements of the flexible exosuit 1100 h during locomotion or duringother activities of the wearer, as described herein.

FIG. 11I illustrates elements of a flexible exosuit 1100 i configured toapply an extensor torque to the ankle 1107 i of a wearer 1105 i. Theflexible exosuit 1100 i includes a motor 1110 i rigidly coupled to afirst FTE 1130 i. The first force-transmitting element 1130 i isconfigured to couple forces to the calf of the wearer 1105 i. Theflexible exosuit 1100 i additionally includes first 1140 i and second1150 i rigid force-transmitting elements (RFTEs). The first RFTE 1140 iis connected to the first FTE 1130 i and the second RFTE 1150 i throughbearings 1132 i and 1142 i, respectively. The second RFTE 1150 i isconnected to a second FTE 1120 i through a bearing 1152 i. Second FTE1120 i is configured to couple forces from bearing 1152 i and a twistedstring 1112 i connected to the posterior of the second FTE 1120 i to thefoot of the wearer 1105 i. The twisted string 1112 e is also connectedto a rotor of the motor 1110 i.

Operation of the motor 1110 i causes a force to be applied such that theposterior of the second FTE 1120 i is pulled toward the motor 1110 i.This can result in an extensor torque being applied to the ankle of thewearer 1105 i. Operation of flexible exosuit 1100 i to apply such anextensor torque can result in significant compressive loading of theankle 1107 i and shear and/or normal forces transmitted into skin of thecalf of the wearer 1105 i by the first FTE 1130 i.

The flexible exosuit 1100 i additionally includes a first exotendon 1162i connected between the first FTE 1130 i and the second FTE 1120 i and asecond exotendon 1164 i connected between the posterior end of the firstRFTE 1140 i and the posterior end of the second RFTE 1150 i. The firstand second exotendons 1162 i, 1164 i could be operated to clutch andun-clutch elements having a specified compliance (e.g., springs, straps)included in the exotendons 1162 i, 1164 i to store and release elasticpotential energy and/or to modulate the impedance of elements of theflexible exosuit 1100 i during locomotion or during other activities ofthe wearer, as described herein. Further, the first and secondexotendons 1162 i, 1164 i could be operated to reduce the compressiveloading of the ankle 1107 i and the shear and/or normal forcestransmitted into skin of the calf of the wearer 1105 i by the first FTE1130 i when the flexible exosuit 1100 i is operated to apply an extensortorque to the ankle of the wearer 1105 i.

Note that FIGS. 11A-11I show simplified, cross-sectional schematic viewsof elements of respective flexible exosuits 1100 a-1100 i. Some or allof the elements of flexible exosuits 1100 a-1100 i could be duplicatedand the original and duplicate elements disposed on opposite sides ofthe leg of the respective wearer 1105 a-1105 i. Additionally oralternatively, elements of flexible exosuits 1100 a-1100 i could beconfigured to wholly or partially encircle parts of respective wearers'1105 a-1105 i bodies such that forces and/or torques transmitted betweenelements and/or between elements and parts of respective wearers' 1105a-1105 i bodies are applied substantially along a plane bisecting localelements (e.g., joints) of respective wearers' 1105 a-1105 i bodies(e.g., along a mid-sagittal plane of a leg in the illustrated examples).Further, elements described as ‘bearings’ (e.g., 1132 d,e,g,h,i, 1142d,e,g,h,i, 1162 d) could be any variety of bearings (e.g., plainbearings, ball bearings, roller bearings, fluid bearings) or could beother elements configured to allow a rotation between elements but notto allow translation (e.g., a ball-and-socket joint), according to anapplication. Additionally, illustrated ‘bearings’ (e.g., 1132 d,e,g,h,i,1142 d,e,g,h,i, 1162 d) could include rods or pins configured to rigidlycouple duplicate, paired elements (as described above) on opposite sidesof an aspect of a wearer's body. Further, note that where rods and/orpins are shown, other rotational or other joints could be used accordingto an application. For example, hinge joints, ball-and-socket joints,Hardy-Spicer joints, or other joints could be used according to anapplication requiring two elements to not be able to translate but to beable to rotate in one or more dimensions.

Configurations of actuators and rigid and flexible force-transmittingelements in a flexible exosuit can additionally enable the transmissionof compressive forces from a first segment of a wearer's body to asecond segment. This can be accomplished using electrically-operatedelements such that the flexible exosuit could operate the actuators tominimally encumber relative motion of the first and second segments.FIGS. 12A and 12B illustrate side and back views, respectively, of partsof a flexible exosuit 1200 configured to selectively transmitcompressive forces between the thigh and the calf of a wearer 1205.

The flexible exosuit 1200 includes first 1210 and second 1220 rigidforce-transmitting elements (RFTEs). The first 1210 and second 1220RFTEs are connected together by bearings 1216, 1217 configured to allowthe first 1210 and second 1220 RFTEs to rotate relative to each other.When the flexible exosuit 1200 is worn by the wearer 1205 (as shown inFIG. 12A), an axis of rotation of the bearings 1216, 1217 is locatedproximate to, by not necessarily coaxial with, an axis of rotation ofthe knee 1207 of the wearer 1205. The flexible exosuit 1200 isconfigured such that relatively unencumbered motion of the wearer's 1205knee and/or operation of the flexible exosuit 1200 to transmitcompressive forces between the thigh and calf of the wearer 1205 are notcontingent upon a precise alignment of the axis of rotation of thebearings 1216, 1217 and the axis of rotation of the knee 1207. The first1210 and second 1220 RFTEs are connected at first 1214 and second 1224attachment points, respectively, to first 1212 and second 1222 forcecoupling elements (FCEs), respectively. The FCEs 1212, 1222 can includerigid and/or flexible elements as described elsewhere in this disclosureand are configured to transmit forces transmitted to the FCEs 1212, 1222from the RFTEs 1210, 1220 through the attachment points 1214, 1224,respectively, into skin of the thigh and calf, respectively, of thewearer 1205.

The flexible exosuit 1200 includes exotendons 1230, 1231 having firstends rigidly coupled to the second RFTE 1220 and second ends connectedto respective cables 1232, 1233 that wrap around respective pulleys1234, 1235 on the second RFTE 1220. The cables 1232, 1233 then connectto respective attachment points 1236, 1237 on the first RFTE 1210. Whenthe exotendons 1230, 1231 are unclutched, the RFTEs 1210, 1220 canrotate about each other in response to movement of the knee of thewearer 1205. When the exotendons 1230, 1231 are clutched, rotation ofthe RFTEs 1210, 1220 about the bearings 1216, 1217 can be prevented bytensile forces transmitted between the RFTEs 1210, 1220 by the cables1232, 1233. As a result, a compressive force could be transmitted by theflexible exosuit 1200 between the thigh and calf of the wearer 1205through the attachment points 1214, 1224 when the exotendons 1230, 1231are clutched.

The illustrated elements of the flexible exosuit 1200 are only oneexample of how elements of a flexible exosuit could be configured toallow transmission of compressive forces from a first segment of awearer's body to a second segment while being able to be operated tosubstantially not encumber relative motion of the first and second bodysegments. In some examples, the actuator could include a twisted stringactuator or some other flexible or rigid linear actuator, a rotationalactuator (e.g., a motor, a clutch), or could include a combination ofactuators (e.g., a STEM). For example, instead of the exotendon, cable,and pulley system illustrated in FIGS. 12A and 12B, a mechanical clutchcould be situated on or near the bearings 1216, 1226 to prevent relativemotion of the RFTEs 1210, 1220. The mechanical clutch could beconfigured to prevent rotation of the bearings in either direction,allowing the flexible exosuit 1200 to transmit both compressive andtensile forces. Additionally or alternatively, additional cables,pulleys, and other elements could enable at least one exotendon toprevent rotation of the bearings 1216, 1226 in one or both directions,allowing the flexible exosuit 1200 to transmit compressive and/ortensile forces between segments of a user's body.

Further, the illustrated flexible exosuit 1200 could include additionalor alternate elements to enable additional functionality. Flexiblestraps or other elements could be connected to the RFTEs 1210, 1220 tomaintain the RFTEs 1210, 1220 close to the leg of the wearer 1205 and/orto maintain some minimum alignment between the axis of rotation of thebearings 1216, 1217 and the axis of rotation of the knee 1207 whileallowing the flexible exosuit 1200 to be operated so as to notsubstantially encumber relative motion of the thigh and calf of thewearer 1205. The shape of the second RFTE 1220, the composition ofsurface coatings of the second RFTE 1220 and/or the exotendons 1230,1231, or some other aspect of the flexible exosuit 1200 could bespecified to enhance the clutching force of the exotendons 1230, 1231through the capstan effect. That is, the flexible exosuit 1200 could beconfigured such that a significant fraction of the force transmitted bythe cables 1232, 1233 between the RFTEs 1210, 1220 is transmitted intothe second RFTE 1210 through friction between a surface of the secondRFTE 1220 (and/or a surface of some element rigidly mechanically coupledto the second RFTE 1220) and surfaces of the cables 1232, 1233 and/orexotendons 1230, 1231. Other configurations of a flexible exosuitconfigured to transmit compressive forces between body segments of awearer are anticipated.

The illustration of elements of a flexible exosuit configured to applyforces between the calf and the foot of a wearer, as in FIGS. 11A-11I,or forces between the calf and the thigh or a wearer, as in FIGS.12A-12B, are intended as examples. A flexible exosuit could includesimilar structures to transmit compressive and/or tensile forces betweendifferent segments of a wearer's body and/or across different joints ofa wearer's body. For example, structures similar to those illustrated inFIGS. 11A-11I and/or FIGS. 12A-12B could, with minimal modification, beconfigured to apply torques to elbows, wrists, shoulders, hips, knees,ankles, and/or other joints and/or combinations of joint of a wearer.Additionally, the use of twisted string actuators in FIGS. 11A-11E and11G-11I and the use of exotendons in FIGS. 11H-I and FIGS. 12A-B aremeant as illustrative examples of actuators. Additionally oralternatively, flexible linear actuators, twisted string actuators,exotendons, EPAMs, STEMs, motor-and-drum-driven cables, servos,pneumatic or hydraulic pistons, racks and pinions, motorized screwdrives or ball screws, or other actuators could be used in place of theillustrated twisted string actuators or exotendons according to anapplication.

X. Endo-Herr Model of Lower-limb Locomotion

FIG. 13A illustrates a schematic diagram of the Endo-Herr model 1300 ofthe human leg. The model can be used to simulate locomotion of the legusing a reduced set of actuators, i.e., three active force transducersand seven exotendons. The model includes rigid elements representing thebones of the leg and torso; specifically, the model includes the foot1310 a, tibia 1310 b, femur 1310 c, and torso and pelvis 1310 d. Themodel additionally includes pin joints representing the in-planemovements of the joints of the leg, including the ankle 1315 a, knee 131b, and hip 1315 c. The bones and joints can include simulated propertiesaccording to their analogous elements of human anatomy, includingmasses, moments of inertia, friction and damping coefficients, or otherproperties.

The model 1300 includes force transducers comprising a force-generatingelement connected in series with a spring. These force transducers areintended to simulate some of the properties of muscles, including theability to add energy to the leg during locomotion. The forcetransducers include an ankle plantarflexor 1330 a connected between thetibia 1310 b and a spring 1325 that is connected in turn to the foot1310 a, such that the ankle plantarflexor 1330 a and spring 1325together cross the ankle 1315 a. The force transducers additionallyinclude a hip extensor 1330 b and a hip flexor 1330 c connected betweenthe torso and pelvis 1310 d and the femur 1310 c across the hip 1315 c.Properties of the force transducers 1330 a, 1330 b, 1330 c could bechosen to represent elements of human anatomy, available artificialtransducers, or according to some other constraint or application.

The model 1300 includes exotendons comprising a clutch connected inseries with a spring. These exotendons are intended to simulate some ofthe properties of tendons, including the ability to store energy from,dissipate energy from, and/or and release stored energy to the legduring locomotion. The exotendons additionally include the clutch,enabling the energy storage and/or compliance of the exotendons to bemodulated during movement of the simulated leg to enable more efficientlocomotion. The exotendons include a knee extensor 1320 c and a kneeflexor 1320 f connected between the femur 1310 c and the tibia 1310 bacross the knee 1315 b. The exotendons additionally include a posteriorfemur exotendon 1320 g and an anterior femur exotendon 1320 b connectedbetween the torso and pelvis 1310 d and the tibia 1310 b across both thehip 1315 c and knee 131 b. The exotendons additionally include a hipflexor 1320 a connected between the torso and pelvis 1310 d and thefemur 1310 c across the hip 1315 c. The exotendons additionally includean ankle dorsiflexor 1320 d connected between the tibia 1310 b and thefoot 1310 a across the ankle 1315 a. The exotendons additionally includea posterior tibia exotendon 1320 e connected between the femur 1310 cand the spring 1325 that is connected in turn to the foot 1310 a, suchthat the posterior tibia exotendon 1320 e and spring 1325 together crossthe ankle 1315 a and knee 1315 b. Properties of the exotendons 1320 a,1320 b, 1320 c, 1320 d, 1320 e, 1320 f, 1320 g and spring 1325 could bechosen to represent elements of human anatomy, available artificialexotendons or other clutched-compliance components, or according to someother constraint or application.

The model 1300 can be used to simulate the effect of a sequence ofactivations of clutches of the exotendons and/or force-generatingelements of the force transducers on a leg. A sequence of suchsimulations could be used to develop sets of exotendon properties, forcetransducer properties, clutch and force-generating element activationtimings, and/or other model properties to optimize some metric. Forexample, simulations using the model could be used to develop a set ofclutch and force-generating element activation timings to enablesimulated locomotion using minimal energy. Other metrics could beoptimized, including system stability, perturbation tolerance, segmentjerk, joint angular acceleration, instantaneous power use, or otherfactors.

The model 1300 could be used to develop control algorithms for flexibleexosuits, prosthetics, assistive devices, or other applications of ordevices relating to the human leg. For example, a prosthetic leg couldbe configured to reflect the configuration of elements in the model 1300(i.e., to include force transducer-like and exotendon-like elements).The prosthetic leg could then be operated to locomote according to anoutput of the model 1300, e.g., a set of clutch and force-generatingelement activation timings. In another example, the model 1300 could beused to test and/or train a controller for a device configured toreflect the configuration of elements in the model 1300 (e.g., theprosthetic above, or a flexible exosuit). That is, gains, timings,topologies, or other aspects of a controller could be optimized,trained, validated, or otherwise specified based on simulationsperformed using the model. Other uses and applications of the model 1300are anticipated.

In some examples, the model 1300 could be used to determine jointangles, joint angular velocities, joint torques, and other variables oflocomotion across a stereotypical locomotor cycle. This stereotypicallocomotor cycle could be determined by including additional constraintsto the behavior of the model, e.g., by attempting to develop a stable,maximally efficient locomotor cycle. From the determined informationabout the stereotypical locomotor cycle, a mapping or other relationshipbetween a set of joint angles, a set of joint angular velocities, alocomotor phase, and/or a set of joint torques. For example, given a setof joint angles and joint angular velocities, one could determine acorresponding locomotor phase (e.g., a point 60% from the beginning ofthe stereotypical locomotor phase). One could then determine a set ofjoint torques corresponding to the determined locomotor phase.

The Endo-Herr model 1300, or some other model including the Endo-Herrmodel 1300, could be implemented as part of a controller of a flexibleexosuit, prosthetic, assistive device, or other device related to ahuman leg. For example, a controller be configured to generate a set ofactivations for clutches and force-generating elements in the model 1300based on sensed information about the human leg (e.g., joint angles,joint velocities, joint torques, user interface commands from the ownerof the leg, etc.). An implementation of the model 1300 could be includedin the controller and could be configured to generate a simulated set ofjoint torques based on the generated set of activations. Another elementof the controller could be configured to operate a flexible exosuit orother device interacting with the human leg to create torques about thehuman leg approximating the set of simulated joint torques produced bythe implementation of the model 1300. Additionally or alternatively, acontroller could be configured to generate a set of joint torques for ahuman leg based on sensed information about the human leg. An inverseimplementation of the model 1300 could be included in the controller togenerate a set of activations for clutches and force-generating elementsand to operate a flexible exosuit or other device interacting with thehuman leg based on the generated set of activations. Other uses andimplementations of the Endo-Herr model 1300, or some other modelincluding the Endo-Herr model 1300 are anticipated.

Properties and patterns of operation of the exotendons 1320 a, 1320 b,1320 c, 1320 d, 1320 e, 1320 f, 1320 g, spring 1325, and forcetransducers 1330 a, 1330 b, 1330 c could be chosen to mimic forces,moments, movements, or other properties of locomotion recorded from ahuman. For example, a pattern of torques applied by muscles of a humanto bones of the human while the human walks could be recorded. Theproperties and patterns of actuation of elements (e.g., 1320 a-g, 1325,1330 a-c) of the Endo-Herr model 1300 could be specified such that thetorques applied to the joints 1315 a-c of the simulated skeleton 1310a-d by the elements 1320 a-g, 1325, 1330 a-c of the Endo-Herr model 1300mimicked the torqued recorded from the human and/or maximized some costfunction related to the recorded torques and/or the simulated workperformed by the elements 1320 a-g, 1325, 1330 a-c of the Endo-Herrmodel 1300.

FIG. 14 illustrates timing patterns 1400 for operating exotendons 1320a-g and force transducers 1330 a-c to mimic a pattern of joint torquerecorded from a human during locomotion. The timing patterns 1400represent the timing of activation of exotendons 1320 a-g and forcetransducers 1330 a-c relative to a normalized locomotor cycle, i.e.,from 0% of a walking or running step (defined as the moment the heel ofthe foot strikes the ground, the first heel strike 1401) to 100%(defined as the moment of the subsequent heel strike, the second heelstrike 1403). The moment the foot lifts from ground surface (thebeginning of swing 1407) is also illustrated. The black bars indicateperiods of the normalized locomotor cycle wherein an individual actuatoris active, that is, when an exotendon 1320 a-g is clutched or a forcetransducer 1330 a-c is being operated to produce a tensile force.

The levels of activation (not shown) and timing of activation (1430 a-c)of the force transducers (1330 a-c, respectively) are specified toproduce a simulated torque at the hip 1315 c (using 1430 b and 1430 c)and at the ankle 1315 a that mimics the recorded torques. The simulatedhip torque mimics the recorded torque exactly due to the presence ofindependent hip extensor 1330 c and hip flexor 1330 b force actuators.The simulated ankle torque 1411 is produced partially by the ankleextensor force actuator 1330 a and closely matches the recorded ankletorque.

The specified compliances and timings of actuation 1420 a-g ofrespective exotendons 1320 a-g are specified using an optimizationprocess to maximize correspondence between the simulated joint torques1411, 1413 and recorded joint torques, to simulated energy used by theforce transducers 1330 a-c, or according to some other cost function,combination of cost functions, or some other constraints and/orconsiderations. Recorded torque patterns could be from an individual,from a population of individuals, or from some other source (e.g., apattern of torque determined from a model or simulation to be in someway optimal for crouched locomotion, jumping, running, or some otherapplication of lower limbs of a human). Further, the parameters of theEndo-Herr model 1300 that is used to generate the levels and patterns ofactuator activation 1400 could be specified based on a specificindividual (e.g., the weight of the body segments 1310 a-d could berelated to a weight of an individual) and/or a specific physicalimplementation of elements of the Endo-Herr model 1300 (e.g., thecompliances of the exotendons 1320 a-g could be specified based on thecompliances of corresponding exotendons of a flexible exosuit configuredto mimic the configuration of elements of the Endo-Herr model 1300). Thelevels and patterns of actuator activation 1400 produced from a modelhaving parameters specified for a specific individual and/or physicalimplementation of the Endo-Herr model 1300 could be used to operateelements of the specific physical implementation of the Endo-Herr model1300 being used to apply forces and/or torques to the specificindividual.

More complicated methods of control of the simulated elements of theEndo-Herr model 1300 to effect some simulated behavior or goal could beimplemented. Controllers could include state machines, feedback loops,feed-forward controllers, look-up tables (LUTs),proportional-integral-derivative (PID) controllers, inverse kinematicmodels, state-space controllers, bang-bang controllers,linear-quadratic-Gaussian (LQG) controllers, other controllers and/orcombinations of controllers. Parameters, topologies, or other aspects ofconfiguration of a controller could be optimized (according to someconstraint or cost function similar to the cost functions and constraintoutlined above, or according to some other application) in simulationbefore being used to control a specific physical implementation of theEndo-Herr model 1300 being used to apply forces and/or torques to aspecific individual and/or some other physical application. Parametersof the Endo-Herr model 1300 that is used to simulate the operation of acontroller could be specified based on a specific individual and/or aspecific physical implementation of elements of the Endo-Herr model1300.

FIG. 15A illustrates a set of state machine controllers 1510, 1520, 1530configured to operate simulated force transducers 1330 a-c andexotendons 1320 a-g of the Endo-Herr model 1300. Each of the statemachine controllers 1510, 1520, 1530 changes state based on respectiveevents in the locomotor cycle. Further, each of the state machinecontrollers 1510, 1520, 1530 is configured to operate elements of theEndo-Herr model 1300 of a respective joint; that is, 1510 controlselements 1330 a, 1320 d related to the ankle 1315 a, 1520 controlselements 1320 b, 1320 c, 1320 e, 1320 f, 1320 g related to the knee 1315b, 1530 controls elements 1330 b, 1330 c related to the hip 1315 c.Further, a number of dynamical controllers (not shown) can be activatedby the state machine controllers 1510, 1520, 1530 to control theamplitude of forces generated by the force transducers 1330 a-c.Further, the exotendons 1320 b-g are configured to clutch duringspecified transitions of respective state machine controllers 1510,1520, 1530 and to un-clutch when the force transmitted by respectiveexotendons 1320 b-g becomes substantially zero subsequent to clutching.

The ankle state machine controller 1510 has first 1511, second 1513, andthird 1515 states. The ankle state machine controller 1510 transitionsfrom the third 1515 to the first 1511 states when the foot 1310 a firstmakes contact with the ground (also known as heel strike); thistransition results in the clutching of exotendon 1520 d. The ankle statemachine controller 1510 transitions from the first 1511 to the second1513 states when the foot 1310 a first becomes flat on the ground theground; this transition results in the ankle force transducer 1330 abeing controlled by a force-feedback controller configured to actuatethe ankle force transducer 1330 a to generate forces such that the aground reaction force between the foot 1310 a and the ground is a setlevel. The first 1511 and second 1513 states could be consideredanalogous to the stance phase of human locomotion. The ankle statemachine controller 1510 transitions from the second 1513 to the third1515 states when the foot 1310 a first leaves contact with the ground;this transition results in the ankle force transducer 1330 a beingcontrolled by a low-gain proportional-derivative (PD) controllerconfigured to actuate the ankle force transducer 1330 a to generateforces such the angle of the ankle joint 1315 a is a set level. The setlevel could be specified such that the foot 1310 a made contact with theground heel-first. The third state 1515 could be considered analogous tothe swing phase of human locomotion.

The hip state machine controller 1530 has first 1531 and second 1533states. The hip state machine controller 1510 transitions from thesecond 1533 to the first 1531 states when the foot 1310 a first makescontact with the ground (also known as heel strike); this transitionresults in the hip force transducers 1330 b, 1330 c being controlled bya first PD controller configured to actuate the hip force transducers1330 b, 1330 c to generate forces such the angle of the hip joint 1315 cis a set level. The set level could be specified such that elements ofthe Endo-Herr model 1300 leg swung forward enough during each simulatedlocomotor cycle to enable forward movement. The hip state machinecontroller 1510 transitions from the first 1531 to the second 1533states when the knee 1315 b reaches maximum extension during the swingphase (i.e., when the ankle state machine controller 1510 occupies thethird state 1515); this transition results in the hip force transducers1330 b, 1330 c being controlled by a second PD controller configured toactuate the hip force transducers 1330 b, 1330 c to generate forces suchthe angle between the torso and pelvis 1310 d segment and gravity is aset level. The set level could be specified such that elements of theEndo-Herr model 1300 are stable (i.e., such that the elements do notfall over).

The knee state machine controller 1520 has first 1521, second 1523,third 1525, and fourth 1527 states. The knee state machine controller1520 transitions from the fourth 1527 to the first 1521 states when theknee 1315 b reaches maximum flexion during the stance phase (i.e., whenthe ankle state machine controller 1510 occupies either the first 1511or second 1513 states); this transition results in the clutching ofexotendon 1520 e. The knee state machine controller 1520 transitionsfrom the first 1521 to the second 1523 states when the foot 1310 a firstleaves contact with the ground; this transition results in the clutchingof exotendon 1520 b. The knee state machine controller 1520 transitionsfrom the second 1523 to the third 1525 states when the knee 1315 b angleequals 48 degrees following maximum knee 1315 b flexion during the swingphase (i.e., when the ankle state machine controller 1510 occupies thethird state 1515); this transition results in the clutching ofexotendons 1520 f and 1520 g. The knee state machine controller 1520transitions from the third 1525 to the fourth 1527 states when the knee1315 b reaches maximum extension during the swing phase (i.e., when theankle state machine controller 1510 occupies the third state 1515); thistransition results in the clutching of exotendon 1520 c.

FIG. 15B illustrates the time course of state machine controller states1551, 1553, 1555 (first 1510, second 1520, and third 1530 state machinecontrollers, respectively), simulated joint angles 1561 b, 1563 b, 1565b (ankle 1315 a, knee 1315 b, and hip 1315 c, respectively), andsimulated joint torques 1571 b, 1573 b, 1575 b (ankle 1315 a, knee 1315b, and hip 1315 c, respectively), over a normalized locomotor cycleresulting from operating the elements of the Endo-Herr model 1300 usingthe state machine controllers 1510, 1520, 1530 as described above.Additionally, joint angles 1561 a, 1563 a, 1565 a (ankle 1315 a, knee1315 b, and hip 1315 c, respectively) and joint torques 1571 a, 1573 a,1575 a (ankle 1315 a, knee 1315 b, and hip 1315 c, respectively) areshown in FIG. 15B to show that the state machine controllers 1510, 1520,1530 can operate the elements of the Endo-Herr model 1300 in abiofidelic manner; i.e., similarly to the patterns with which a humanuses muscles to effect locomotion.

The Endo-Herr model 1300 could be implemented as part of a larger model.FIG. 13B illustrates a combined model 1350 that includes elementscorresponding to elements of the Endo-Herr model 1300 (elements 1312a-d, 1317 a-c, 1322 a-g, 1327, 1332 a-c, corresponding respectively toelements 1310 a-d, 1315 a-c, 1320 a-g, 1325, 1330 a-c). Rigid elementscorresponding to the foot, tibia, femur, and torso and pelvis (1312 a,1312 b, 1312 c, and 1312 d, respectively) have geometrical extents andother properties in addition to the properties of the correspondingelements (1310 a, 1310 b, 1310 c, and 1310 d) of the Endo-Herr model1300. The geometrical extents and relative positions of the rigidelements 1312 a, 1312 b, 1312 c, 1312 d could be based on anatomicaldata from an individual human, an anatomical database, a description ofan idealized ‘mean’ human skeleton, or some other source. Properties ofthe force transducers 1332 a, 1332 b, 1332 c, exotendons 1322 a, 1322 b,1322 c, 1322 d, 1322 e, 1322 f, 1322 g, and spring 1325 could be chosento represent elements of a prosthetic, a flexible exosuit, availableartificial transducers, or according to some other constraint orapplication.

The combined model 1350 additionally includes simulated muscles 1352.The locations, origins, insertions, actions, biomechanical properties,slack lengths, force-velocity curves, and other properties of thesimulated muscles 1352 could be based on physiological and anatomicaldata from an individual human, a database of physiological and/oranatomical data from a plurality of humans, a statistical valuecalculated from a database of physiological and/or anatomical data froma plurality of humans, or some other source.

The combined model 1350 could be used to model a wearer of a flexibleexosuit or some other assistive device during locomotion or other tasks.The activation of the simulated muscles 1352, movement of the rigidelements 1312 a, 1312 b, 1312 c, 1312 d, and other aspects of suchsimulations could be defined by data collected from individual users.Additionally or alternatively, the activation of the simulated muscles1352, movement of the rigid elements 1312 a, 1312 b, 1312 c, 1312 d, andother aspects of such simulations could be based on ongoing propertiesof such simulations; for example, simulated muscle 1352 activationscould be generated by a simulated nervous system or other controllerbased on the state of the combined model 1352 and/or the locations ofthe rigid elements 1312 a, 1312 b, 1312 c, 1312 d could be based onkinematics, torques or other outputs of the combined model 1352.Simulations using the combined model 1350 could include the presence ofsimulated loads rigidly or otherwise attached to the simulated torso andpelvis 1312 d.

The combined model 1350 could be used to develop control algorithms forflexible exosuits, prosthetics, assistive devices, or other applicationsof or devices relating to the human leg. For example, the model 1350could be used to test and/or train a controller for a device configuredto reflect the configuration of non-anatomical elements in the model1350 (e.g., a flexible exosuit). That is, gains, timings, topologies, orother aspects of a controller could be optimized, trained, validated, orotherwise specified based on simulations performed using the combinedmodel 1350 model. The combined model 1350 could be used to train acontroller to activate elements of the device to assist a non-simulatedleg of a wearer of the device to perform some activity, e.g.,locomotion, jumping, and/or to perform sort activity in a manner that ismore optimal in some way, e.g., more efficiently. Additionally oralternatively, the combined model 1350 could be used to train acontroller to activate elements of the device to prevent injury of anon-simulated leg of a wearer of the device while allowing the wearer touse the leg relatively unimpeded. Other uses and applications of thecombined model 1350 are anticipated.

XI. Configurations of Actuators in Flexible Exosuits

A flexible exosuit may be configured in a variety of ways according to avariety of applications. Indeed, it is this versatility in the choice ofelements and software that establishes the exosuit as a humanaugmentation platform for the variety of applications. Further, aflexible exosuit may be configured according to an overall topology(e.g., having a twisted string actuator configured to apply a flexortorque to a knee of a wearer and an exotendon configured to apply anextensor torque to an ankle of a wearer) and additionally have specificparameters or measurements specified according to an individual wearerand/or be configured to have one or more parameters or measurementsadjustable to accommodate an individual wearer. A flexible exosuit maybe configured to apply forces to the lower body, upper body, torso, orcombinations of some or all of these parts of a wearer. A flexibleexosuit could be symmetric (able to apply the same types of forces andtorques to one side of a wearer's body as to the opposite side) or couldbe asymmetric (e.g., to enable strength assists and/or rehabilitation toa wearer that has experienced an injury to one limb and not to theopposite limb). Different overall topologies of configuration offlexible exosuits may correspond to and/or be specified by respectiveapplications of flexible exosuits.

FIGS. 16A, 16B, and 16C show side, front, and back views, respectively,of a schematic illustrating actuators of a flexible exosuit 1600 beingworn by a wearer 1605 on the wearer's 1605 torso and lower limbs. Theankle 1615 a, Knee 1615 b, and hip 1615 c of the wearer 1605 areillustrated to indicate which joints of the wearer 1605 are crossed byindividual actuators 1620 a-g, 1630 a-c of the flexible exosuit 1600.The flexible exosuit includes flexible linear actuators 1630 a, 1630 b,1630 c (e.g., twisted string actuators (TSAs)) configured to applyextensor torque to the ankle 1615 a, extensor torque to the hip 1615 c,and flexor torque to the hip 1615 c, respectively. The flexible exosuit1600 additionally includes clutched-compliance elements 1620 a, 1620 b,1620 c, 1620 d, 1620 e, 1620 f, 1620 g (e.g., exotendons) configured toapply a flexor force to the lower torso/lower back of the wearer 1605,flexor torque to the hip 1615 c and extensor torque to the knee 1615 b,extensor torque to the knee 1615 b, flexor torque to the ankle 1615 a,flexor torque to the knee 1615 b and extensor torque to the ankle 1615a, flexor torque to the knee 1615 b, and extensor torque to the hip 1615c and flexor torque to the knee 1615 b, respectively. Theclutched-compliance elements could be configured to enable switchingbetween different levels of compliance and/or to enable the storage andlater release of mechanical energy.

The flexible exosuit 1600 could include other elements and actuators(not shown). The flexible exosuit 1600 could include sensors to detectone or more properties of the flexible exosuit 1600, the wearer 1605,and/or the environment of the flexible exosuit 1600. The sensors couldbe discrete, or could be incorporated into assemblies with or integratedas part of the actuators 1620 a-g, 1630 a-c. The sensors could includeaccelerometers, gyroscopes, strain gauges, load cells, encoders,displacement sensors, capacitive sensors, biosensors, thermometers, orothers types of sensors. The flexible exosuit 1600 could includefeedback elements, including haptic feedback elements that could beoperated to indicate information to the wearer 1605. Additionally oralternatively, the actuators 1620 a-g, 1630 a-c could be operated toindicate haptic information to the wearer 1605. The flexible exosuitcould additionally include controllers, batteries, engines, fuel cells,communications devices, user interfaces, or other elements as describedherein or as are familiar to one of skill in the art to enable functionsand applications of the flexible exosuit 1600.

Note that a flexible exosuit need not be capable of independentactuation of each joint or degree of freedom of a wearer's body that iscovered by the flexible exosuit. That is, the flexible exosuit could beunder-actuated, and the degrees of freedom of the wearer's body that areactuated could be specified according to an application of the flexibleexosuit. For example, the flexible exosuit 1600 illustrated in FIGS.16A-C is underactuated, i.e., the flexible exosuit 1600 is unable toindependently actuate (e.g., apply independent torques to usingtension-generating actuators 1630 a, 1630 b, 1630 c) all of the joints1615 a, 1615 b, 1615 c of the wearer's 1605 lower limb. Theconfiguration of actuators in the flexible exosuit 1600 is related tothe pattern of simulated actuators in the Endo-Herr reduced model ofefficient bipedal locomotion.

The flexible exosuit 1600 is sufficiently actuated to enable variousapplications and uses of the flexible exosuit 1600. The flexible exosuitcould be operated to prevent the development of fatigue during extendedlocomotion by the wearer by extracting, storing, and/or injecting energyto/from the legs of the wearer 1605. The flexible exosuit 1600 could beoperated to increase the maximum load carried by the wearer 1605 byadding extensor torques to the joints of the legs of the wearer 1605and/or by operating the clutched-compliance elements 1620 a-g tomodulate the effective impedance of the joints 1615 a-c of the wearer1615 to reduce the development of fatigue. The flexible exosuit 1600could be operated to prevent injury of the wearer 1605, for example, byincreasing the effective joint impedance and/or limiting the range ofmotion of a joint that was about to experience an injury-inducing amountof torque, force, and/or angular displacement.

FIG. 17 shows a schematic illustrating actuators of a flexible exosuit1700 being worn by a wearer 1705 on the wearer's 1705 torso and upperlimbs. The shoulder 1715 a, elbow 1715 b, and wrist 1715 c of the wearer1705 are illustrated to indicate which joints of the wearer 1705 arecrossed by individual actuators 1720 a-b, 1730 of the flexible exosuit1700. The flexible exosuit includes a flexible linear actuator 1730(e.g., a twisted string actuator (TSA)) configured to apply extensortorque to upper torso of the wearer 1705. The flexible exosuit 1700additionally includes clutched-compliance elements 1720 a, 1720 b (e.g.,exotendons) configured to transmit a supportive force to a load held inthe hand of the wearer 1705 to the shoulder and/or upper torso of thewearer 1705. The clutched-compliance elements could be configured toenable switching between different levels of compliance and/or to enablethe storage and later release of mechanical energy.

The flexible exosuit 1700 could be operated to assist the wearer 1705 incarrying heavy loads and/or reducing the development of fatigue in thearms of the wearer while carrying a load for a prolonged period of time.For example, the clutched-compliance elements 1720 a, 1720 b could bedeactivated (i.e., substantially slack, high-compliance, andnon-interfering with motions of the wearer 1705) when the wearer 1705 isnot carrying a load. When the wearer 1705 is carrying a load, theclutched-compliance elements 1720 a, 1720 b could be activated such thatthe clutched-compliance elements 1720 a, 1720 b are substantiallynon-compliant, such that the force necessary to carry the load istransferred between the wearer's upper torso by the flexible exosuit1700 instead of by the muscles and other active,metabolic-energy-consuming, fatigue-able elements of the wearer's 1705arm. The flexible exosuit 1700 could additionally or alternatively beoperated to enable other functions; for example, the actuators 1720 a-b,1730 could be operated to effect a specified posture of the arm of thewearer 1705, e.g., to effect greater accuracy of operation of a weapon.In another example, the flexible exosuit 1700 could be operated toassists the wearer 1705 in climbing, e.g., by assisting the wearer 1705by using the tension-generating actuator 1730.

The illustration of elements of a flexible exosuit in FIGS. 16A-B andFIG. 17 are intended as examples. A flexible exosuit could includeactuators in a similar or different arrangement according to anapplication. In some examples, elements of a flexible exosuit couldallow the arms and legs of the body of a wearer to be controllablymechanically coupled. For example, exotendons could be disposed in anexosuit to couple motions of the arms of a wearer to motions of the legsof a wearer. This configuration could enable a wearer to use thewearer's arms to assists the wearer's legs in walking, running,sprinting, climbing, or some other activity. Other alternateconfigurations and applications of a flexible exosuit are anticipated.Additionally, illustrated twisted string actuators and exotendons aremeant as illustrative examples of actuators. Additionally oralternatively, twisted string actuators, exotendons, EPAMs, STEMs,motor-and-drum-driven cables, servos, pneumatic or hydraulic pistons,racks and pinions, motorized screw drives or ball screws, or otheractuators could be used in place of the illustrated twisted stringactuators or exotendons according to an application.

XII. Methods for Controlling and Applications of an Exosuit

A flexible exosuit or similar mechatronic system could be operated byelectronic controllers disposed on or within the flexible exosuit or inwireless or wired communication with the flexible exosuit. Theelectronic controllers could be configured in a variety of ways tooperate the flexible exosuit and to enable functions of the flexibleexosuit. The electronic controllers could access and executecomputer-readable programs that are stored in elements of the exosuit orin other systems that are in direct or indirect communications with theflexible exosuit. The computer-readable programs could describe methodsfor operating the flexible exosuit or could describe other operationsrelating to a flexible exosuit or to a wearer of a flexible exosuit.

FIG. 18 illustrates an example flexible exosuit 1800 that includesactuators 1801, sensors 1803, and a controller configured to operateelements of the flexible exosuit 1800 (e.g., 1801, 1803) to enablefunctions of the flexible exosuit 1800. The controller 1805 isconfigured to communicate wirelessly with a user interface 1810. Theuser interface 1810 is configured to present information to a user(e.g., a wearer of the flexible exosuit 1800) and to the controller 1805of the flexible exosuit or to other systems. The user interface 1810could be involved in controlling and/or accessing information fromelements of the flexible exosuit 1800 (e.g., 101, 1803). For example, anapplication being executed by the user interface 1810 could access datafrom the sensors 1803, calculate an operation (e.g., to apply a torqueof 50 newton-meters to the knee of a wearer for 200 milliseconds) of theactuators 1801, and transmit the calculated operation to the flexibleexosuit 100. The user interface 1810 could additionally be configured toenable other functions; for example, the user interface 1810 could beconfigured to be used as a cellular telephone, a portable computer, anentertainment device, or to operate according to other applications.

The user interface 1810 could be configured to be removably mounted tothe flexible exosuit 1800 (e.g., by straps, magnets, Velcro, chargingand/or data cables). Alternatively, the user interface 1810 could beconfigured as a part of the flexible exosuit 1800 and not to be removedduring normal operation. In some examples, a user interface could beincorporated as part of the flexible exosuit 1800 (e.g., a touchscreenintegrated into a sleeve of the flexible exosuit 1800) and could be usedto control and/or access information about the flexible exosuit 1800 inaddition to using the user interface 1810 to control and/or accessinformation about the flexible exosuit 1800. In some examples, thecontroller 1805 or other elements of the flexible exosuit 1800 areconfigured to enable wireless or wired communication according to astandard protocol (e.g., Bluetooth, ZigBee, WiFi, LTE or other cellularstandards, IRdA, Ethernet) such that a variety of systems and devicescould be made to operate as the user interface 1810 when configured withcomplementary communications elements and computer-readable programs toenable such functionality.

The flexible exosuit 1800 could be configured as described in exampleembodiments herein or in other ways according to an application. Theflexible exosuit 1800 could be operated to enable a variety ofapplications. The flexible exosuit 1800 could be operated to enhance thestrength of a wearer by detecting motions of the wearer (e.g., usingsensors 1803) and responsively applying torques and/or forces to thebody of the wearer (e.g., using actuators 1801) to increase the forcesthe wearer is able to apply to his/her body and/or environment. Thiscould include enabling a wearer to lift heavier objects or to jumphigher than the wearer would be able to when not wearing the flexibleexosuit 1800. This could include allowing a wearer to walk or run whilecarrying a load or while unencumbered farther than the wearer would beable to when not wearing the flexible exosuit 1800 by providing somefraction of the ground reaction forces or other forces and/or torquesthat the wearer generates while locomoting. Further, elements of theflexible exosuit 1800 could be operated to reduce and/or meter fatigueof the wearer by supplementing the forces and/or torques that the wearergenerates with a specified fraction of the forces and/or torques bysuing the actuators 1801. The specified fraction could be constant,could be related to a detected fatigue state of the wearer (e.g.,detected using the sensors 1803), or could be based on some otherconsideration.

The flexible exosuit 1800 could be operated to avoid and/or reduceinjuries experienced by a wearer. In some examples, reducing the fatigueexperienced by a wearer (by operating the suit as described herein tosupplement forces generated by the wearer to perform tasks, or accordingto other applications) can reduce the probability that the wearerexperiences joint damage, sprains, strains, or other injuries. Theactuators 1801 (e.g., exotendons) could be operated to increase theeffective impedance of a wearer's joints to reduce the forces and/ortorques experienced by the joints during a fall or other injury-inducingevent. Additionally or alternatively, actuators 1801 of the flexibleexosuit 1800 could be operated to ensure that joints of the wearer wereable to move freely in certain directions but not in other directionslikely to result in injury (e.g., an ankle could be able to move freelyto dorsiflex and/or plantarflex, but not to rotate in directions otherthan the dorsiflexion/plantarflexion direction (e.g.,adduction/abduction)), or to ensure that the rate and/or extent of jointmotion does not exceed some safety threshold.

The flexible exosuit 1800 could be operated to avoid and/or reduceinjuries experienced by a wearer by operating actuators 1801continuously (e.g., by continuously operating actuators to reduce theeffective impedance of a joint of the wearer) or could operate theactuators 1803 in response to a detected condition (e.g., by the sensors1803). For example, the sensors 1803 could detect that a rate of jointmovement was above a threshold, and the actuators 1801 could beresponsively operated to increase the effective impedance of the joint.In some examples, the flexible exosuit 1800 could operate the actuators1803 to avoid and/or reduce the occurrence of injuries in response tothe presence of unstable or otherwise dangerous terrain or otherdangerous environmental conditions. For example, the flexible exosuit1800 could include LIDAR, radar, ultrasonic rangefinders, or othersensors configured to detect that terrain in front of a wearer isuneven. Additionally or alternatively, the flexible exosuit 1800 couldreceive information from the server 1830 about the terrain in front ofthe wearer. The flexible exosuit 1800 could then be operated to avoidand/or reduce the occurrence of injuries to the wearer in response toinformation indicating that the terrain was uneven.

The flexible exosuit 1800 could be operated to train a wearer to performcertain physical activities. For example, the flexible exosuit 1800could be operated to enable rehabilitative therapy of a wearer. Theflexible exosuit 1800 could operate to amplify motions and/or forcesproduced by a wearer undergoing therapy in order to enable the wearer tosuccessfully complete a program of rehabilitative therapy. Additionallyor alternatively, the flexible exosuit 1800 could be operated toprohibit disordered movements of the wearer and/or to use the actuators1801 and/or other elements (e.g., haptic feedback elements) to indicateto the wearer a motion or action to perform and/or motions or actionsthat should not be performed or that should be terminated. Similarly,other programs of physical training (e.g., dancing, skating, otherathletic activities, vocational training) could be enabled by operationof the flexible exosuit 1800 to detect motions, torques, or forcesgenerated by a wearer and/or to apply forces, torques, or other hapticfeedback to the wearer. Other applications of the flexible exosuit 1800and/or user interface 1810 are anticipated.

The flexible exosuit 1800 could be operated to perform any of thedescribed functions (e.g., training, injury prevention, fatiguereduction) while the wearer performs a variety of tasks. In someexamples, the flexible exosuit 1800 could be worn by a wearer engaged inathletic activities. The flexible exosuit 1800 could be worn by a wearerengaging in cycling; the flexible exosuit 1800 could be operated totrain the wearer to use a more effective stroke, to help the wearer toengage in more effective pacing, or some other application. The flexibleexosuit 1800 could be worn by a wearer who was walking, running, orotherwise locomoting and the flexible exosuit 1800 could be operated toincrease the efficiency of the wearer's locomotion. In some examples,the wearer could be walking in an environment that was unfamiliar to thewearer and/or that includes some hazards, and the flexible exosuit 1800could be operated to train the wearer to walk in a manner that minimizeda chance of injury, maximized an efficient, speed, or other constraint,to protect the wearer from injury, or according to some otherapplication. For example, the wearer could be using snow shoes to walkacross snowy terrain, and the flexible exosuit 1800 could be operated totrain the wearer in an efficient gait for locomoting across the snowyterrain and/or could apply forces and/or torques to the wearer to assistthe wearer in locomoting. In some examples, the flexible exosuit 1800could act as a ‘golf coach,’ by guiding the movements of a wearer (usinge.g., haptic feedback elements, exotendons, TSAs) to teach the wearer toperform a golf stroke having an optimal trajectory, timing, or otherproperties. The wearer could perform the movements to perform the golfstroke repeatedly, and could learn proper technique from the guidance ofthe flexible exosuit 1800.

The flexible exosuit 1800 could be operated to make it more difficultfor the wearer to perform a task (e.g., a task that may be harmful tothe wearer). That is, the flexible exosuit 1800 could be operated toapply forces and/or torques to the body of the wearer such that thewearer had to exert more effort to perform a task (e.g., walking,running, climbing) than the wearer would have to exert if the flexibleexosuit 1800 was not being operated in that way. This operation of theflexible exosuit 1800 could enable more effective strength and/orcardiovascular training. In some examples, the flexible exosuit 1800could be operated to act as a ‘virtual gym’, allowing the wearer toperform exercises against forces and/or torques generated by theflexible exosuit 1800 as though the wearer was interacting with exerciseequipment (e.g., a treadmill, an elliptical machine). For example, theflexible exosuit 1800 could be operated to apply forces to the arms ofthe wearer, to simulate the presence of free weights being used by thewearer. Further, the flexible exosuit 1800 could be operated to enableexercise regimens that would be expensive or impossible to implementusing standalone gym equipment. In some examples, the flexible exosuit1800 could be operated to apply forces and/or torques to the body of thewearer to simulate other environments. For example, the forces and/ortorques could simulate for the wearer the experience of performingunderwater (or in some other fluid, by simulated the increased drag thewearer would experience underwater), in a heavy wind (e.g., assistingmotions of the wearer in the direction of the simulated wind, andhindering motions in the opposite direction), performing in a differentgravity field (e.g., on the moon, on a world with higher gravity thanthe earth), or other environments.

The user interface 1810 can additionally communicate with communicationsnetwork(s) 1820. For example, the user interface 1810 could include aWiFi radio, an LTE transceiver or other cellular communicationsequipment, a wired modem, or some other elements to enable the userinterface 1810 and flexible exosuit 1800 to communicate with theInternet. The user interface 1810 could communicate through thecommunications network 1820 with a server 1830. Communication with theserver 1830 could enable functions of the user interface 1810 andwearable exosuit 1800. In some examples, the user interface 1810 couldupload telemetry data (e.g., location, configuration of elements 1801,1803 of the flexible exosuit 1800, physiological data about a wearer ofthe flexible exosuit 1800) to the server 1830.

In some examples, the server 1830 could be configured to control and/oraccess information from elements of the flexible exosuit 1800 (e.g.,1801, 1803) to enable some application of the flexible exosuit 1800. Forexample, the server 1830 could operate elements of the flexible exosuit1800 to move a wearer out of a dangerous situation if the wearer wasinjured, unconscious, or otherwise unable to move themselves and/oroperate the exosuit 1800 and user interface 1810 to move themselves outof the dangerous situation. Other applications of a server incommunications with a flexible exosuit are anticipated.

The user interface 1810 could be configured to communicate with a seconduser interface 1845 in communication with and configured to operate asecond flexible exosuit 1840. Such communication could be direct (e.g.,using radio transceivers or other elements to transmit and receiveinformation over a direct wireless or wired link between the userinterface 1810 and the second user interface 1845). Additionally oralternatively, communication between the user interface 1810 and thesecond user interface 1845 could be facilitated by communicationsnetwork(s) 1820 and/or a server 1830 configured to communicate with theuser interface 1810 and the second user interface 1845 through thecommunications network(s) 1820.

Communication between the user interface 1810 and the second userinterface 1845 could enable applications of the flexible exosuit 1800and second flexible exosuit 1840. In some examples, actions of theflexible exosuit 1800 and second flexible exosuit 1840 and/or of wearersof the flexible exosuit 1800 and second flexible exosuit 1840 could becoordinated. For example, the flexible exosuit 1800 and second flexibleexosuit 1840 could be operated to coordinate the lifting of a heavyobject by the wearers. The timing of the lift, and the degree of supportprovided by each of the wearers and/or the flexible exosuit 1800 andsecond flexible exosuit 1840 could be controlled to increase thestability with which the heavy object was carried, to reduce the risk ofinjury of the wearers, or according to some other consideration.Coordination of actions of the flexible exosuit 1800 and second flexibleexosuit 1840 and/or of wearers thereof could include applyingcoordinated (in time, amplitude, or other properties) forces and/ortorques to the wearers and/or elements of the environment of the wearersand/or applying haptic feedback (though actuators of the exosuits 1800,1840, through dedicated haptic feedback elements, or through othermethods) to the wearers to guide the wearers toward acting in acoordinated manner.

Coordinated operation of the flexible exosuit 1800 and second flexibleexosuit 1840 could be implemented in a variety of ways. In someexamples, one flexible exosuit (and the wearer thereof) could act as amaster, providing commands or other information to the other flexibleexosuit such that operations of the exosuits 1800, 1840 are coordinated.For example, the exosuits 1800, 1840 could be operated to enable thewearers to dance (or to engage in some other athletic activity) in acoordinated manner. One of the flexible exosuits could act as the‘lead’, transmitting timing or other information about the actionsperformed by the ‘lead’ wearer to the other flexible exosuit, enablingcoordinated dancing motions to be executed by the other wearer. In someexamples, a first wearer of a first exosuit could act as a trainer,modeling motions or other physical activities that a second wearer of asecond exosuit could learn to perform. The first exosuit could detectmotions, torques, forces, or other physical activities executed by thefirst wearer and could send information related to the detectedactivities to the second exosuit. The second exosuit could then applyforces, torques, haptic feedback, or other information to the body ofthe second wearer to enable the second wearer to learn the motions orother physical activities modeled by the first wearer. In some examples,the server 1830 could send commands or other information to the exosuits1800, 1840 to enable coordinated operation of the exosuits 1800, 1840.

Note that more than the two illustrated flexible exosuits 1800, 1840 canbe operated in a coordinated manner. In some examples, many flexibleexosuits or other mechatronic or other systems could be operated in acoordinated manner to enable some application. For example, a troupe ofballet dancers, a team of football players, a team of synchronizedskaters, a marching band, a mime troupe, or some other groups ofathletes or performers could be wearing flexible exosuits configured tocoordinate their motions in time. In some examples, a first wearer of afirst exosuit could act as a trainer or coach, modeling motions or otherphysical activities that many wearers of respective flexible exosuitscould learn to perform. The first exosuit could detect motions, torques,forces, or other physical activities executed by the first wearer andcould send information related to the detected activities to the manyother flexible exosuits. The many other exosuits could then applyforces, torques, haptic feedback, or other information to the bodies ofrespective wearers to enable the wearers to learn the motions or otherphysical activities modeled by the first wearer. In some examples, aserver could send commands or other information to a plurality ofexosuits to enable coordinated operation of the plurality of exosuits.Other applications including the coordinated operation of a plurality offlexible exosuits are anticipated.

The flexible exosuit 1800 could be operated to transmit and/or recordinformation about the actions of a wearer, the environment of thewearer, or other information about a wearer of the flexible exosuit1800. In some examples, kinematics related to motions and actions of thewearer could be recorded and/or sent to the server 1830. These datacould be collected for medical, scientific, entertainment, social media,or other applications. The data could be used to operate a system. Forexample, the flexible exosuit 1800 could be configured to transmitmotions, forces, and/or torques generated by a user to a robotic system(e.g., a robotic arm, leg, torso, humanoid body, or some other roboticsystem) and the robotic system could be configured to mimic the activityof the wearer and/or to map the activity of the wearer into motions,forces, or torques of elements of the robotic system. In anotherexample, the data could be used to operate a virtual avatar of thewearer, such that the motions of the avatar mirrored or were somehowrelated to the motions of the wearer. The virtual avatar could beinstantiated in a virtual environment, presented to an individual orsystem with which the wearer is communicating, or configured andoperated according to some other application.

Conversely, the flexible exosuit 1800 could be operated to presenthaptic or other data to the wearer. In some examples, the actuators 1801(e.g., twisted string actuators, exotendons) and/or haptic feedbackelements (e.g., EPAM haptic elements) could be operated to apply and/ormodulate forces applied to the body of the wearer to indicate mechanicalor other information to the wearer. For example, the activation in acertain pattern of a haptic element of the flexible exosuit 1800disposed in a certain location of the flexible exosuit 1800 couldindicate that the wearer had received a call, email, or othercommunications. In another example, a robotic system could be operatedusing motions, forces, and/or torques generated by the wearer andtransmitted to the robotic system by the flexible exosuit 1800. Forces,moments, and other aspects of the environment and operation of therobotic system could be transmitted to the flexible exosuit 1800 andpresented (using actuators 1801 or other haptic feedback elements) tothe wearer to enable the wearer to experience force-feedback or otherhaptic sensations related to the wearer's operation of the roboticsystem. In another example, haptic data presented to a wearer could begenerated by a virtual environment, e.g., an environment containing anavatar of the wearer that is being operated based on motions or otherdata related to the wearer that is being detected by the flexibleexosuit 1800.

Note that multiple functions, applications, or other operations of theflexible exosuit 1800 as described herein or according to otherapplications may be executed simultaneously. For example, a flexibleexosuit could be operated to reduce fatigue of a wearer by supplementingthe forces and/or torques generated by muscles of the wearer. Sensors inthe exosuit or other systems (e.g., remote servers, drones) couldprovide an indication to the flexible exosuit, while the flexibleexosuit is being operated to reduce wearer fatigue, that the ground infront of the wearer is unstable. The flexible exosuit could beresponsively operated to increase the effective impedance of the anklesof the wearer to reduce the probability of the wearer experiencing anankle sprain or strain due to locomoting on the unstable ground.Simultaneous operation could include linearly or nonlinearly summingactuator commands generated according to multiple applications (e.g.,fatigue reduction and injury prevention), a first application blockingoperation by a second application of certain actuators required by thefirst application during a period of time the first application isrequired to operate the certain actuators, or other schemes of operationof an exosuit according to multiple applications simultaneously.

Note that the flexible exosuit 1800 illustrated in FIG. 18 is only oneexample of a flexible exosuit that could be operated by controlelectronics, software, or algorithms described herein. Controlelectronics, software, or algorithms as described herein could beconfigured to control flexible exosuits or other mechatronic and/orrobotic system having more, fewer, or different actuators, sensors orother elements. Further, control electronics, software, or algorithms asdescribed herein could be configured to control flexible exosuitsconfigured similarly to or differently from the illustrated flexibleexosuit 1800. Further, control electronics, software, or algorithms asdescribed herein could be configured to control flexible exosuits havingreconfigurable hardware (i.e., exosuits that are able to have actuators,sensors, or other elements added or removed) and/or to detect a currenthardware configuration of the flexible exosuits using a variety ofmethods.

Software Hierarchy for Control of a Flexible Exosuit

A controller of a flexible exosuit and/or computer-readable programsexecuted by the controller could be configured to provide encapsulationof functions and/or components of the flexible exosuit. That is, someelements of the controller (e.g., subroutines, drivers, services,daemons, functions) could be configured to operate specific elements ofthe flexible exosuit (e.g., a twisted string actuator, a haptic feedbackelement) and to allow other elements of the controller (e.g., otherprograms) to operate the specific elements and/or to provide abstractedaccess to the specific elements (e.g., to translate a command to orientan actuator in a commanded direction into a set of commands sufficientto orient the actuator in the commanded direction). This encapsulationcould allow a variety of services, drivers, daemons, or othercomputer-readable programs to be developed for a variety of applicationsof a flexible exosuits. Further, by providing encapsulation of functionsof a flexible exosuit in a generic, accessible manner (e.g., byspecifying and implementing an application programming interface (API)or other interface standard), computer-readable programs can be createdto interface with the generic, encapsulated functions such that thecomputer-readable programs could enable operating modes or functions fora variety of differently-configured flexible exosuits, rather than for asingle type or model of flexible exosuit. For example, a virtual avatarcommunications program could access information about the posture of awearer of a flexible exosuit by accessing a standard exosuit API.Differently-configured exosuits could include different sensors,actuators, and other elements, but could provide posture information inthe same format according to the API. Other functions and features of aflexible exosuit, or other robotic, exoskeletal, assistive, haptic, orother mechatronic system, could be encapsulated by APIs or according tosome other standardized computer access and control interface scheme.

FIG. 19 is a schematic illustrating elements of a flexible exosuit 1900and a hierarchy of control or operating the flexible exosuit 1900. Theflexible exosuit includes actuators 1920 and sensors 1930 configured toapply forces and/or torques to and detect one or more properties of,respectively, the flexible exosuit 1900, a wearer of the flexibleexosuit 1900, and/or the environment of the wearer. The flexible exosuit1900 additionally includes a controller 1910 configured to operate theactuators 1920 and sensors 1930 by using hardware interface electronics1940. The hardware electronics interface 1940 includes electronicsconfigured to interface signals from and to the controller 1910 withsignals used to operate the actuators 1920 and sensors 1930. Forexample, the actuators 1920 could include exotendons, and the hardwareinterface electronics 1940 could include high-voltage generators,high-voltage switches, and high-voltage capacitance meters to clutch andun-clutch the exotendons and to report the length of the exotendons. Thehardware interface electronics 1940 could include voltage regulators,high voltage generators, amplifiers, current detectors, encoders,magnetometers, switches, controlled-current sources, DACs, ADCs,feedback controllers, brushless motor controllers, or other electronicand mechatronic elements.

The controller 1910 additionally operates a user interface 1950 that isconfigured to present information to a user and/or wearer of theflexible exosuit 1900 and a communications interface 1960 that isconfigured to facilitate the transfer of information between thecontroller 1910 and some other system (e.g., by transmitting a wirelesssignal). Additionally or alternatively, the user interface 1950 could bepart of a separate system that is configured to transmit and receiveuser interface information to/from the controller 1910 using thecommunications interface 1960 (e.g., the user interface 1950 could bepart of a cellphone).

The controller 1910 is configured to execute computer-readable programsdescribing functions of the flexible exosuit 1912. Among thecomputer-readable programs executed by the controller 1910 are anoperating system 1912, applications 1914 a, 1914 b, 1914 c, and acalibration service 1916. The operating system 1912 manages hardwareresources of the controller 1910 (e.g., I/O ports, registers, timers,interrupts, peripherals, memory management units, serial and/or parallelcommunications units) and, by extension, manages the hardware resourcesof the flexible exosuit 1900. The operating system 1912 is the onlycomputer-readable program executed by the controller 1910 that hasdirect access to the hardware interface electronics 1940 and, byextension, the actuators 1920 and sensors 1930 of the flexible exosuit1900.

The applications 1914 a, 1914 b, 1914 are computer-readable programsthat describe some function, functions, operating mode, or operatingmodes of the flexible exosuit 1900. For example, application 1914 acould describe a process for transmitting information about the wearer'sposture to update a virtual avatar of the wearer that includes accessinginformation on a wearer's posture from the operating system 1912,maintaining communications with a remote system using the communicationsinterface 1960, formatting the posture information, and sending theposture information to the remote system. The calibration service 1916is a computer-readable program describing processes to store parametersdescribing properties of wearers, actuators 1920, and/or sensors 1930 ofthe flexible exosuit 1900, to update those parameters based on operationof the actuators 1920, and/or sensors 1930 when a wearer is using theflexible exosuit 1900, to make the parameters available to the operatingsystem 1912 and/or applications 1914 a, 1914 b, 1914 c, and otherfunctions relating to the parameters. Note that applications 1914 a,1914 b, 1914 and calibration service 1916 are intended as examples ofcomputer-readable programs that could be run by the operating system1912 of the controller 1910 to enable functions or operating modes of aflexible exosuit 1900.

The operating system 1912 could provide for low-level control andmaintenance of the hardware (e.g., 1920, 1930, 1940). In some examples,the operating system 1912 and/or hardware interface electronics 1940could detect information about the flexible exosuit 1900, the wearer,and/or the wearer's environment from one or more sensors 1930 at aconstant specified rate. The operating system 1912 could generate anestimate of one or more states or properties of the flexible exosuit1900 or components thereof using the detected information. The operatingsystem 1912 could update the generated estimate at the same rate as theconstant specified rate or at a lower rate. The generated estimate couldbe generated from the detected information using a filter to removenoise, generate an estimate of an indirectly-detected property, oraccording to some other application. For example, the operating system1912 could generate the estimate from the detected information using aKalman filter to remove noise and to generate an estimate of a singledirectly or indirectly measured property of the flexible exosuit 1900,the wearer, and/or the wearer's environment using more than one sensor.In some examples, the operating system could determine information aboutthe wearer and/or flexible exosuit 1900 based on detected informationfrom multiple points in time. For example, the operating system 1900could determine a gait phase (e.g., stance, swing, heel strike, toe-off)and/or gait phase percent while the wearer is locomoting based ondetected joint angles, body segment locations, actuator loads, or otherdetected information from multiple past points in time.

In some examples, the operating system 1912 and/or hardware interfaceelectronics 1940 could operate and/or provide services related tooperation of the actuators 1920. That is, in case where operation of theactuators 1920 requires the generation of control signals over a periodof time, knowledge about a state or states of the actuators 1920, orother considerations, the operating system 1912 and/or hardwareinterface electronics 1940 could translate simple commands to operatethe actuators 1920 (e.g., a command to generate a specified level offorce using a twisted string actuator (TSA) of the actuators 1920) intothe complex and/or state-based commands to the hardware interfaceelectronics 1940 and/or actuators 1920 necessary to effect the simplecommand (e.g., a sequence of currents applied to windings of a motor ofa TSA, based on a starting position of a rotor determined and stored bythe operating system 1910, a relative position of the motor detectedusing an encoder, and a force generated by the TSA detected using a loadcell).

In some examples, the operating system 1912 could further encapsulatethe operation of the flexible exosuit 1900 by translating a system-levelsimple command (e.g., a commanded level of torque applied to the knee ofa wearer) into commands for multiple actuators, according to theconfiguration of the flexible exosuit 1900 (e.g., command signalssufficient to cause a TSA and exotendons that cross the knee of thewearer to apply forces to the body of the wearer such that the commandedlevel of torque is applied to the knee of the wearer). Thisencapsulation could enable the creation of general-purpose applicationsthat can effect a function of an exosuit (e.g., allowing a wearer of theexosuit to jump higher) without being configured to operate a specificmodel or type of exosuit (e.g., by being configured to generate a simpleankle torque profile that the operating system 1912 and hardwareinterface electronics 1940 could translate into actuator commandssufficient to cause the actuators 1920 to apply the commanded torqueprofile to the ankle).

The operating system 1912 could act as a standard, multi-purposeplatform to enable the use of a variety of flexible exosuits having avariety of different hardware configurations to enable a variety ofmechatronic, biomedical, human interface, training, rehabilitative,communications, and other applications. The operating system 1912 couldmake sensors 1930, actuators 1920, or other elements or functions of theflexible exosuit 1900 available to remote systems in communication withthe flexible exosuit 1900 (e.g., using the communications interface1960) and/or a variety of applications, daemons, services, or othercomputer-readable programs being executed by operating system 1912. Theoperating system 1912 could make the actuators, sensors, or otherelements or functions available in a standard way (e.g., through an API,communications protocol, or other programmatic interface) such thatapplications, daemons, services, or other computer-readable programscould be created to be installed on, executed by, and operated to enablefunctions or operating modes of a variety of flexible exosuits having avariety of different configurations. The API, communications protocol,or other programmatic interface made available by the operating system1912 could encapsulate, translate, or otherwise abstract the operationof the flexible exosuit 1900 to enable the creation of suchcomputer-readable programs that are able to operate to enable functionsof a wide variety of differently-configured flexible exosuits.

Additionally or alternatively, the operating system 1912 could beconfigured to operate a modular flexible exosuit system (i.e., aflexible exosuit system wherein actuators, sensors, or other elementscould be added or subtracted from a flexible exosuit to enable operatingmodes or functions of the flexible exosuit). In some examples, theoperating system 1912 could determine the hardware configuration of theflexible exosuit 1900 dynamically and could adjust the operation of theflexible exosuit 1900 relative to the determined current hardwareconfiguration of the flexible exosuit 1900. This operation could beperformed in a way that was ‘invisible’ to computer-readable programs(e.g., 1914 a, 1914 b, 1914 c) accessing the functionality of theflexible exosuit 1900 through a standardized programmatic interfacepresented by the operating system 1912. For example, thecomputer-readable program could indicate to the operating system 1912,through the standardized programmatic interface, that a specified levelof torque was to be applied to an ankle of a wearer of the flexibleexosuit 1900. The operating system 1912 could responsively determine apattern of operation of the actuators 1920, based on the determinedhardware configuration of the flexible exosuit 1900, sufficient to applythe specified level of torque to the ankle of the wearer.

In some examples, the operating system 1912 and/or hardware interfaceelectronics 1940 could operate the actuators 1920 to ensure that theflexible exosuit 1900 does not operate to directly cause the wearer tobe injured and/or elements of the flexible exosuit 1900 to be damaged.In some examples, this could include not operating the actuators 1920 toapply forces and/or torques to the body of the wearer that exceeded somemaximum threshold. This could be implemented as a watchdog process orsome other computer-readable program that could be configured (whenexecuted by the controller 1910) to monitor the forces being applied bythe actuators 1920 (e.g., by monitoring commands sent to the actuators1920 and/or monitoring measurements of forces or other propertiesdetected using the sensors 1930) and to disable and/or change theoperation of the actuators 1920 to prevent injury of the wearer.Additionally or alternatively, the hardware interface electronics 1940could be configured to include circuitry to prevent excessive forcesand/or torques from being applied to the wearer (e.g., by channeling toa comparator the output of a load cell that is configured to measure theforce generated by a TSA, and configuring the comparator to cut thepower to the motor of the TSA when the force exceeded a specifiedlevel).

In some examples, operating the actuators 1920 to ensure that theflexible exosuit 1900 does not damage itself could include a watchdogprocess or circuitry configured to prevent over-current, over-load,over-rotation, or other conditions from occurring that could result indamage to elements of the flexible exosuit 1900. For example, thehardware interface electronics 1940 could include a metal oxidevaristor, breaker, shunt diode, or other element configured to limit thevoltage and/or current applied to a winding of a motor.

Note that the above functions described as being enabled by theoperating system 1912 could additionally or alternatively be implementedby applications 1914 a, 1914 b, 1914 c, services, drivers, daemons, orother computer-readable programs executed by the controller 1900. Theapplications, drivers, services, daemons, or other computer-readableprograms could have special security privileges or other properties tofacilitate their use to enable the above functions.

The operating system 1912 could encapsulate the functions of thehardware interface electronics 1940, actuators 1920, and sensors 1930for use by other computer-readable programs (e.g., applications 1914 a,1914 b, 1914 c, calibration service 1916), by the user (through the userinterface 1950), and/or by some other system (i.e., a system configuredto communicate with the controller 1910 through the communicationsinterface 1960). The encapsulation of functions of the flexible exosuit1900 could take the form of application programming interfaces (APIs),i.e., sets of function calls and procedures that an application runningon the controller 1910 could use to access the functionality of elementsof the flexible exosuit 1900. In some examples, the operating system1912 could make available a standard ‘exosuit API’ to applications beingexecuted by the controller 1910. The ‘exosuit API’ could enableapplications 1914 a, 1914 b, 1914 c to access functions of the exosuit1900 without requiring those applications 1914 a, 1914 b, 1914 c to beconfigured to generate whatever complex, time-dependent signals arenecessary to operate elements of the flexible exosuit 1900 (e.g.,actuators 1920, sensors 1930).

The ‘exosuit API’ could allow applications 1914 a, 1914 b, 1914 c tosend simple commands to the operating system 1912 (e.g., ‘begin storingmechanical energy from the ankle of the wearer when the foot of thewearer contacts the ground’) in such that the operating system 1912 caninterpret those commands and generate the command signals to thehardware interface electronics 1940 or other elements of the flexibleexosuit 1900 that are sufficient to effect the simple commands generatedby the applications 1914 a, 1914 b, 1914 c (e.g., determining whetherthe foot of the wearer has contacted the ground based on informationdetected by the sensors 1930, responsively applying high voltage to anexotendon that crosses the user's ankle).

The ‘exosuit API’ could be an industry standard (e.g., an ISO standard),a proprietary standard, an open-source standard, or otherwise madeavailable to individuals that could then produce applications forexosuits. The ‘exosuit API’ could allow applications, drivers, services,daemons, or other computer-readable programs to be created that are ableto operate a variety of different types and configurations of exosuitsby being configured to interface with the standard ‘exosuit API’ that isimplemented by the variety of different types and configurations ofexosuits. Additionally or alternatively, the ‘exosuit API’ could providea standard encapsulation of individual exosuit-specific actuators (i.e.,actuators that apply forces to specific body segments, wheredifferently-configured exosuits may not include an actuator that appliesforces to the same specific body segments) and could provide a standardinterface for accessing information on the configuration of whateverflexible exosuit is providing the ‘exosuit API’. An application or otherprogram that accesses the ‘exosuit API’ could access data about theconfiguration of the flexible exosuit (e.g., locations and forcesbetween body segments generated by actuators, specifications ofactuators, locations and specifications of sensors) and could generatesimple commands for individual actuators (e.g., generate a force of 30newtons for 50 milliseconds) based on a model of the flexible exosuitgenerated by the application and based on the information on theaccessed data about the configuration of the flexible exosuit.Additional or alternate functionality could be encapsulated by an‘exosuit API’ according to an application.

Applications 1914 a, 1914 b, 1914 c could individually enable all orparts of the functions and operating modes of a flexible exosuitdescribed herein. For example, an application could enable hapticcontrol of a robotic system by transmitting postures, forces, torques,and other information about the activity of a wearer of the flexibleexosuit 1900 and by translating received forces and torques from therobotic system into haptic feedback applied to the wearer (i.e., forcesand torques applied to the body of the wearer by actuators 1920 and/orhaptic feedback elements). In another example, an application couldenable a wearer to locomote more efficiently by submitting commands toand receiving data from the operating system 1912 (e.g., through an API)such that actuators 1920 of the flexible exosuit 1900 assist themovement of the user, extract negative work from phases of the wearer'slocomotion and inject the stored work to other phases of the wearer'slocomotion, or other methods of operating the flexible exosuit 1900.Applications could be installed on the controller 1910 and/or on acomputer-readable storage medium included in the flexible exosuit 1900by a variety of methods. Applications could be installed from aremovable computer-readable storage medium or from a system incommunication with the controller 1910 through the communicationsinterface 1960. In some examples, the applications could be installedfrom a web site, a repository of compiled or un-compiled programs on theInternet, an online store (e.g., Google Play, iTunes App Store), or someother source. Further, functions of the applications could be contingentupon the controller 1910 being in continuous or periodic communicationwith a remote system (e.g., to receive updates, authenticate theapplication, to provide information about current environmentalconditions).

The flexible exosuit 1900 illustrated in FIG. 19 is intended as anillustrative example. Other configurations of flexible exosuits and ofoperating systems, kernels, applications, drivers, services, daemons, orother computer-readable programs are anticipated. For example, anoperating system configured to operate a flexible exosuit could includea real-time operating system component configured to generate low-levelcommands to operate elements of the flexible exosuit and a non-real-timecomponent to enable less time-sensitive functions, like a clock on auser interface, updating computer-readable programs stored in theflexible exosuit, or other functions. A flexible exosuit could includemore than one controller; further, some of those controllers could beconfigured to execute real-time applications, operating systems,drivers, or other computer-readable programs (e.g., those controllerswere configured to have very short interrupt servicing routines, veryfast thread switching, or other properties and functions relating tolatency-sensitive computations) while other controllers are configuredto enable less time-sensitive functions of a flexible exosuit.Additional configurations and operating modes of a flexible exosuit areanticipated. Further, control systems configured as described hereincould additionally or alternatively be configured to enable theoperation of devices and systems other than flexible exosuits; forexample, control systems as described herein could be configured tooperate robots, rigid exosuits or exoskeletons, assistive devices,prosthetics, or other mechatronic devices.

Controllers of Mechanical Operation of a Flexible Exosuit

Control of actuators of a flexible exosuit could be implemented in avariety of ways according to a variety of control schemes. Generally,one or more hardware and/or software controllers could receiveinformation about the state of the flexible exosuit, a wearer of theflexible exosuit, and/or the environment of the flexible exosuit fromsensors disposed on or within the flexible exosuit and/or a remotesystem in communication with the flexible exosuit. The one or morehardware and/or software controllers could then generate a controloutput that could be executed by actuators of the flexible exosuit toeffect a commanded state of the flexible exosuits and/or to enable someother application. One or more software controllers could be implementedas part of an operating system, kernel, driver, application, service,daemon, or other computer-readable program executed by a processorincluded in the flexible exosuit.

FIG. 20A illustrates an example process 2000 a for operating a flexibleexosuit that includes detecting a state of the flexible exosuit 2010 a,determining an output based on the detected state using a controller2020 a, and operating the flexible exosuit according to the determinedoutput 2030 a. Detecting a state of the flexible exosuit 2010 a couldinclude measuring one or more properties of the flexible exosuit and/ora wearer thereof using sensors disposed in the flexible exosuit,accessing a stored state of the flexible exosuit, applying a filter(e.g., a Kalman filter) or otherwise processing the measured one or moreproperties and/or accessed stored state, or other processes such thatthe state (i.e., the location, orientation, configuration, and/or otherinformation about elements of the flexible exosuit) of the flexibleexosuit is wholly or partially determined. For example, detecting thestate of the flexible exosuit 2010 a could include determining therelative location and orientation of one or more rigid or semi-rigidsegments of the flexible exosuit and/or one or more segment of the bodyof a wearer of the flexible exosuit.

Determining an output based on the detected state using a controller2020 a could include performing calculations on the detected state,calibration information, information about past detected states,controller parameters, or other information to determine one or moreoutput commands. The calculations could implement one of a variety ofdifferent controllers, according to an application. The controllerscould include state machines, feedback loops, feed-forward controllers,look-up tables (LUTs), proportional-integral-derivative (PID)controllers, parametric controllers, model-based controllers, inversekinematic model-based controllers, state-space controllers, bang-bangcontrollers, linear-quadratic-Gaussian (LQG) controllers, othercontrollers and/or combinations of controllers. Parameters, topologies,or other aspects of configuration of a controller could be optimized,trained, or otherwise validated in simulation before being used tocontrol a flexible exosuit. Parameters of the controller and/or ofsimulations used to validate the controller could be related tocalibration parameters or other data related to a model or type offlexible exosuit, an individual flexible exosuit, an individual wearerof a flexible exosuit, or an environment in which a flexible exosuitcould be operated. The controllers could be configured to improve,adapt, or otherwise reconfigure to improve performance according to somemetric. Such improvement, adaptations, or reconfiguration could berelated to detected or specified changes in properties of the flexibleexosuit and/or the wearer, patterns of usage of the flexible exosuit bythe wearer, gait patterns or other patterns of physical activity ormotion engaged in by the wearer, or other information.

Operating the flexible exosuit according to the determined output 2030 acould include operating twisted string actuators (TSAs), exotendons,electropolymer artificial muscle (EPAM) actuators, or other mechatronicelements to apply forces and/or torques to elements of the flexibleexosuit, the body of the wearer, and/or the environment of the flexibleexosuit. For example, the determined output could specify that a TSAshorten at a specified rate, and operating the flexible exosuitaccording to the determined output 2030 a could include applyingvoltages and/or currents to windings of a motor of the TSA, detecting arate and/or angle of rotation of the motor, or other processes such thatthe TSA shortened at the specified rate. In another example, thedetermined output could specify that a level of torque be applied to ajoint of the wearer, and operating the flexible exosuit according to thedetermined output 2030 a could include operating one or more actuatorsof the flexible exosuit to apply the specified level of torque to thejoint of the wearer. Further, the translation between the determinedoutputs and signals to actuate elements of the flexible exosuit could bebased on calibration data about the actuated elements and/or otheraspects or elements of the flexible exosuit. For example, operating aTSA to shorten at a specified rate could include determining a rate ofrotation to rotate a motor of the TSA based on calibration data thatincludes a transmission ratio of the TSA. Other scenarios and processesas described elsewhere herein are anticipated.

A model-based controller is a controller having a structure,organization, or other features based on or inspired by a mechanical orother model of a system to be controlled by the controller. For example,a model-based controller of an inverted pendulum could be created basedon inverting or otherwise manipulating a model of the response of theinverted pendulum (i.e., the evolution of the states of the invertedpendulum) to control inputs, such that the inverted or otherwisetransformed model generated outputs to control the inverted pendulum(e.g., base forces) to follow a commanded state of the inverted pendulumbased on detected states of the inverted pendulum. In some examples, amodel-based controller includes a model of a system to be controlled andapplies potential and/or current control outputs to the model of thesystem to predict the output of the system in response to the controloutputs, to generate an error signal, or to enable some otherapplication. In some examples, a model-based controller can be a moregeneric type of controller (e.g., PID controller, state-spacecontroller, bang-bang controller, linear-quadratic-Gaussian (LQG)controller) that has parameters trained or otherwise optimized accordingto some cost function or constraint using a simulation of the systemrepresented by the model.

The use of a model-based controller could allow control of the flexibleexosuit to be adapted to different wearers, environments, and conditionswithout a training period. That is, model parameters could be updatedbased on detected changes in properties of the flexible exosuit, thewearer, and/or the environment that correspond to the model parameter.For example, a single model and/or model-based controller could becreated to control flexible exosuits having a specific configuration(e.g., that were configured to include actuators (i.e., TSAs,exotendons) corresponding to the simulated actuators of the Endo-Herrmodel (i.e., force transducers, clutched compliance elements)). Specificparameters of the model-based controller could correspond to propertiesof the wearer and/or elements of the flexible exosuit. For example, theweight of body segments of the wearer, the compliance of an exotendon inthe clutched state, the force-length characteristics of an individualTSA, or other properties could correspond to parameters of a model-basedcontroller. Additionally or alternatively, different operating modes ofthe flexible exosuit (and corresponding applications, services, or othercomputer-readable programs) could correspond to different wearers,environments, and conditions. For example, a first wearer could operatea flexible exosuit using a first configuration service (i.e., a servicethat updates controllers, applications, drivers, configurationparameters, operating modes, applications, or other information relativeto information about the first wearer) and a second wearer could operatethe flexible exosuit using a second configuration service. In someexamples, updates to change model parameters could indicate aqualitative change in a state of the flexible exosuit and/or of thewearer. In some examples, the indicated qualitative change could be anindication that an element of the flexible exosuit was in need ofreplacement and/or likely to fail. For example, updating modelparameters corresponding to a TSA could indicate that the twisted stringof the TSA was significantly fatigued and was likely to break and/or waslikely to cause the TSA to operate in a sub-optimal manner. Thisindication could be conveyed to the wearer through a user interface ofthe flexible exosuit. Additionally or alternatively, the indicationcould be conveyed to a remote system or person (e.g., a repairtechnician, a health technician, a parts manager). In some examples, theindicated qualitative change could be an indication that the wearer hasbecome significantly physically and/or mentally fatigued. Thisindication could be conveyed to the wearer through a user interface ofthe flexible exosuit. Additionally or alternatively, the indicationcould cause the flexible exosuit to change its operation by increasing adegree or percent to which the flexible exosuit augments the activity ofthe wearer and/or inhibits potentially injurious actions or motions ofthe wearer.

In some examples, the use of a model-based controller could enablecontrol of a flexible exosuit based on continuously changing propertiesof the flexible exosuit. That is, the control of the exosuit couldcontinuously adapt to changes in properties of elements of the flexibleexosuit (e.g., force/length/torque properties of TSAs, the compliance ofexotendons as the humidity of the environment of the flexible exosuitchanges). Sensors in the flexible exosuit could generate measurementssufficient to update calibration parameters of elements of the flexibleexosuits (e.g., force/length/torque properties of TSAs, the complianceof exotendons) over time. This calibration process could be performedperiodically by a computer-readable program being executed by acontroller of the flexible exosuit (e.g., calibration service 1916)during operation of the flexible exosuit to effect operating modesand/or during operations of the flexible exosuit directed specificallytoward determining calibration parameters. Additionally oralternatively, individual elements of a flexible exosuit could bereplaceable, and calibration parameters corresponding to a replacementelement could replace calibration parameters stored for an element thatis replaced by the replacement element, such that the flexible exosuithas stored updated calibration parameters about the properties of theelements of the flexible exosuit. The calibration parameters couldcorrespond to parameters of a model-based controller, and calibrationparameters corresponding to the current state of the flexible exosuit(generated, e.g., by a calibration process and/or by replacingcalibration parameters corresponding to a replaced element withparameters corresponding to a replacement element).

Calibration parameters could additionally describe properties of thewearer of the flexible exosuit and/or of loads or other objects carriedby the wearer and/or by the flexible exosuit. For example, a parameterof a model-based controller could correspond to the mass of the wearerabove the wearer's hips (i.e., the mass of the wearer's torso, head, andarms and of any loads carried by or attached to those segments of thewearer's body). Sensors and/or actuators of the flexible exosuit couldbe operated to continuously or periodically estimate the mass of thewearer above the wearer's hips. The parameter of the model-basedcontroller corresponding to that mass could be updated based on theestimated mass of the wearer above the wearer's hips such that, afterupdating the mass parameter of the model based controller, controloutputs determined by the controller take into account the current massof the wearer above the wearer's hips corresponding to the updated massparameter. For example, determined output forces applied by actuators tothe body of the wearer could be increased to compensate for an increasein mass of the wearer above the wearer's hips.

Calibration parameters could be uploaded to a remote system incommunication with the flexible exosuit. Additionally or alternatively,calibration parameters could be downloaded from a remote system incommunication with the flexible exosuit. Sets of calibration parameterscould be associated with specific flexible exosuits, wearers, elementsof flexible exosuits, or combinations thereof. Calibration parametersassociated with a specific wearer and/or a flexible exosuit used by aspecific wearer could be associated with a username, password, or othercredentials to allow the specific wearer to access the storedcalibration parameters over a communications network (e.g., theInternet). Accessing calibration parameters of the specific wearer inthis way could enable the specific wearer to use multiple flexibleexosuits while maintaining easy access to calibration parametersdescribing physical properties of the specific wearer, controllersand/or controller parameters used by the specific wearer, applicationsand/or application data used by the specific wearer, and/or usage, gait,or other patterns related to the specific wearer and/or the specificwearer's operation of flexible exosuits. The username, password, and/orother credentials could secure calibration parameters or otherinformation about a wearer from being accessed by people or systems thatare not the wearer. Additionally or alternatively, a flexible exosuitworn by the wearer could transmit some information about the wearer(e.g., a gait pattern, a gesture made by the wearer) and the informationcould be used as a credential (e.g., as a biometric identifier).

FIG. 20B illustrates an example process 2000 b for operating a flexibleexosuit that includes detecting a state of the flexible exosuit 2010 b,determining an output based on the detected state using a referencefunction 2020 b, and operating the flexible exosuit according to thedetermined output 2030 b. Detecting a state of the flexible exosuit 2010b could include measuring one or more properties of the flexible exosuitand/or a wearer thereof using sensors disposed in the flexible exosuit,accessing a stored state of the flexible exosuit, applying a filter(e.g., a Kalman filter) or otherwise processing the measured one or moreproperties and/or accessed stored state, or other processes such thatthe state (i.e., the location, orientation, configuration, and/or otherinformation about elements of the flexible exosuit) of the flexibleexosuit is wholly or partially determined. For example, detecting thestate of the flexible exosuit 2010 b could include determining therelative location and orientation of one or more rigid or semi-rigidsegments of the flexible exosuit and/or one or more segment of the bodyof a wearer of the flexible exosuit.

Determining an output based on the detected state using a referencefunction 2020 b includes performing some calculation on the detectedstate, where the calculation results in the generation of a determinedoutput. In some examples, determining an output based on the detectedstate using a reference function 2020 b could include transforming thedetected state. In some examples, transforming the detected state couldinclude selecting certain elements of the detected state and discardingother elements. For example, the reference function could be a functionof a detected ankle angle of a wearer, and information in the detectedstate (e.g., angles of other joints, body segment velocities, jointtorques) that are not ankle angles could be discarded. In some examples,transforming the detected state could include scaling, shifting,inverting, or quantizing one or more variables of the detected state. Insome examples, transforming the detected state could include reducingthe dimensionality of the detected state; this is, translating a firstnumber of variables of the detected state into a second number ofvariables that is less than the first number. For example, variables ofthe detected state could be subjected to principal component analysis,independent component analysis, factor analysis, varimax rotation,non-negative matrix factorization, isomap, or some other dimensionalityreduction process. In some examples, transforming the detected statecould include filtering the detected state (e.g., by using a Kalmanfilter, a Wiener filter, or some other linear or nonlinear filter). Insome examples, transforming the detected state could include applyingthe detected state to a classifier. For example, one or more variablesof the detected state could be applied to a support vector machine, ak-nearest-neighbors classifier, or some other classifier of patternmatching algorithm to transform the one or more variables of thedetected state into one of a finite number of output classes.

In some examples, transforming the detected state could include usingthe detected state to determine gait information. For example, thedetected state could be used to determine a gait cycle percent (i.e.,how far, as a percent, ratio, or fraction, through a locomotor cycle awearer of the flexible exosuit is at a current point in time) or a gaitphase (e.g., stance, swing, heel strike, toe off). The gait cyclepercent and/or phase could be determined based on detected joint anglesand/or joint torques of the wearer. For example, measured joint anglesof the detected state could be compared to patterns of recorded jointangles 1561 a, 1563 a, 1565 a, simulated joint angles 1561 b, 1563 b,1565 b, recorded joint torques 1571 a, 1573 a, 1575 a, and/or simulatedjoint torques 1571 b, 1573 b, 1575 b. Recorded and/or simulationpatterns against which the detected state is compared to determine thegait cycle percent and/or phase could be related a specific wearer ofthe flexible exosuit or could be related to a population of wearers orother humans (e.g., the patterns could be mean patterns generated fromdata recorded from a population of humans).

In some examples, determining an output based on the detected stateusing a reference function 2020 b could include applying the determinedstate and/or a transformed version of the determined state to a smoothreference function and calculating the output of the smooth referencefunction to determine the output. The smooth reference function could beunivariate, bivariate, or multivariate and could have one or moreoutputs corresponding to one or more determined outputs based on thedetected state. The smooth reference function could be a polynomial, arational function, an exponential function, a sinusoid, some othersmooth function, or a combination of the above. The shape and/orparameters could be based on a model of some element or function of aflexible exosuit. For example, the smooth reference function could beselected to approximate a force profile produced by a force transducerthat is simulated as part of the Endo-Herr model 1300 to produce stablesimulated locomotion. The shape and/or parameters could be based onrecorded data from a wearer of the flexible exosuit and/or a populationof wearers of flexible exosuits and/or other humans.

In some examples, determining an output based on the detected stateusing a reference function 2020 b could include applying atransformation to the detected state to generate a one or more discreteinput variables and generating the output based on the contents of acell of a look-up table corresponding to the one or more discrete inputvariables. For example, the detected state could be transformed to oneof four possible gait phases (e.g., heel-strike, stance, toe-off, orswing), and each of four possible gait phases could have a correspondingset of outputs (e.g., each gait phase could have a respective set ofexotendons to clutch). The look-up table could have one, two, or morediscrete input variables and could specify the state of one or moreoutputs for each combination of values of the one or more discrete inputvariables. One or more of the discrete input variables could bediscretized and/or quantized continuous variables of the detected state;for example, one of the input variables could be a joint anklediscretized into 50 bins, such that the input variable has fiftydifferent discrete states and the discrete states can be orderedaccording to the relative magnitude of the angles corresponding to thediscrete states. The output values corresponding to the cells of thelook-up table could be based on a model of some element or function of aflexible exosuit. The contents and organization of the cells of thelook-up table and the transformation used to determine which cell of thelook-up table to access for a given detected state could be based onrecorded data from a wearer of the flexible exosuit and/or a populationof wearers of flexible exosuits and/or other humans.

One or more properties of the reference function could be based on amodel of the flexible exosuit, elements of the flexible exosuit, and/ora wearer of the flexible exosuit. In some examples, the referencefunction could be a pattern of activation of some element of theflexible exosuit that has been generated using a model to increase theefficiency of locomotion of the wearer, to decrease a probability ofinjury of the wearer, or to maximize, minimize, and/or satisfy someconstraint. For example, the reference function could be a pattern ofexotendon clutching as a function of gait cycle percent (e.g., 1400). Insome examples, generating the reference function from the model could becomputationally expensive. For example, generating the referencefunction could require gradient descent, a genetic algorithm, and/or thecomputation of one or more simulations of the model. In such examples,the reference function could be generated using the model at a low raterelated to the computational cost of generating the reference function.Additionally or alternatively, the reference function could bere-calculated only when determined, manually input, or otherwisespecified parameters of the model change.

In an example, determining an output based on the detected state using areference function 2020 b includes determining a gait cycle percentbased on detected joint angles of the wearer and actuating exotendons ofa flexible exosuit according to a pattern of activation ofclutched-compliance elements generated using the Endo-Herr model 1300(e.g., 1400). In another example, determining an output based on thedetected state using a reference function 2020 b includes operatingjoint-related state machine controllers that have state transitionsrelated to gait phases (e.g., toe-off, heel-strike, foot-flat) and thatactuate exotendons and operate TSA controllers and that are configuredsimilarly to 1210, 1220, 1230.

Operating the flexible exosuit according to the determined output 2030 bcould include operating twisted string actuators (TSAs), exotendons,electropolymer artificial muscle (EPAM) actuators, or other mechatronicelements to apply forces and/or torques to elements of the flexibleexosuit, the body of the wearer, and/or the environment of the flexibleexosuit. For example, the determined output could specify that a TSAshorten at a specified rate, and operating the flexible exosuitaccording to the determined output 2030 a could include applyingvoltages and/or currents to windings of a motor of the TSA, detecting arate and/or angle of rotation of the motor, or other processes such thatthe TSA shortened at the specified rate. In another example, thedetermined output could specify that a level of torque be applied to ajoint of the wearer, and operating the flexible exosuit according to thedetermined output 2030 b could include operating one or more actuatorsof the flexible exosuit to apply the specified level of torque to thejoint of the wearer. Further, the translation between the determinedoutputs and signals to actuate elements of the flexible exosuit could bebased on calibration data about the actuated elements and/or otheraspects or elements of the flexible exosuit. For example, operating aTSA to shorten at a specified rate could include determining a rate ofrotation to rotate a motor of the TSA based on calibration data thatincludes a transmission ratio of the TSA. Other scenarios and processesas described elsewhere herein are anticipated.

Multiple controllers and/or reference functions could be used todetermine output(s) based on detected states of an exosuit. For example,a first controller could be used to determine outputs during a firstperiod of time and a second controller could be used to determineoutputs during a second period of time. Additionally or alternatively, afirst controller could be used to determine outputs corresponding to afirst set of actuators, joints, or other elements of a flexible exosuitand/or a wearer thereof, and a second controller could be used todetermine outputs corresponding to a second set of actuators, joints, orother elements of a flexible exosuit and/or a wearer thereof that isdisjoint from the first set. Further, one or more controllers,classifiers, or other algorithms could be used to determine whichcontrollers of a set of controllers should be used to generate output(s)and/or how to combine the generated output(s) from the set ofcontrollers to generate a final combined output(s) that could be used tooperate elements of the flexible exosuit.

In some examples, generating a final combined output(s) could includegenerating a linear combination of outputs generated by a set ofcontrollers. For example, a first controller could be configured togenerate output(s) to reduce fatigue of a wearer by supplementing theforces and/or torques generated by muscles of the wearer. A secondcontroller could be configured to generate outputs(s) to increase theeffective impedance of the ankles in response to a determination, basedon the detected state, that the ground in front of the wearer isunstable. Combining the generated output(s) of the two controllers couldinclude linearly or nonlinearly summing actuator commands of thegenerated output(s). Additionally or alternatively, the generatedoutput(s) from the second controller could supersede the generatedoutput(s) from the first controller due to the second controller havinga higher priority than the first controller. Priority could be assignedto controllers according to an application (e.g., controllers thatgenerate outputs(s) relating to injury prevention could have higherpriority than other controllers) and/or priority could be contextdependent (i.e., dependent on a detected state of the flexible exosuit,the wearer, and/or the environment of the flexible exosuit).

In some examples, generated output(s) could be modulated by one or morestate variables of the flexible exosuit. For example, when a powersource of the flexible exosuit is nearly depleted, forces and/or torquesgenerated by the flexible exosuit could be reduced by some fractionrelated to the battery discharge level. In some examples, a fatiguelevel of the wearer could be detected, and forces and/or torquesgenerated by the flexible exosuit could be related to the detectedfatigue level. For example, the forces and/or torques could be increasedwhen the wearer is fatigued, to assist the wearer, to allow the wearerto recover from the fatigue while still engaging in physical activity,and/or to reduce the probability of the wearer experiencingfatigue-related injuries. Additionally or alternatively, the modulationof the forces and/or torques relative to the detected fatigue of thewearer could be implemented according to some other scheme, for example,a pattern configured to maximize the distance a wearer could march by‘dosing’ the fatigue that the wearer accrued over time. In someexamples, the forces and/or torques applied to the wearer by theflexible exosuit could be modulated according to a setting specified bythe wearer. For example, a user interface could allow the wearer toselect a level of assistance and/or augmentation that the flexibleexosuit could apply to the wearer's body according to the comfort of thewearer.

Controllers, models, transformations, filters, reference functions, andother elements and processes described above could be implemented ascomputer-readable programs. The computer-readable programs could be partof an operating system of a flexible exosuit (e.g., 1912) or could beimplemented as applications (e.g., 1914 a-c) being executed by aflexible exosuit and operating in conjunction with an operating system.Applications, services, daemons, or other computer-readable programscould access functions of the flexible exosuit through APIs provided byan operating system. Additionally or alternatively, applications,services, daemons, or other computer-readable programs could providefunctionality to other computer-readable programs by providingadditional APIs or other mechanisms configured to enable access tofunctions of the applications, services, daemons, or othercomputer-readable programs by other computer-readable programs.

The operation of a flexible exosuit could be related to informationinput by a user and/or wearer of the flexible exosuit by interactingwith a user interface. The user interface could be incorporated into theflexible exosuit (e.g., a touchscreen removably or non-removablydisposed in a sleeve of the flexible exosuit) or could be part of aseparate device (e.g., a tablet). Additionally or alternatively, some orall of the user interface of a flexible exosuit could be implemented onsome other device, e.g., a laptop computer or a cellphone. Interactionsof a wearer with a user interface could alter settings or parameters ofthe flexible exosuit, cause the flexible exosuit to change operationalmodes, result in the addition, subtraction, or reconfiguration ofapplications installed on the flexible exosuit, or enable otherfunctions or operating modes of the flexible exosuit.

FIG. 21A illustrates an example of a user interface 2100 a for aflexible exosuit. The user interface 2100 a includes a status variabledisplay 2110 a, an informational schematic 2120 a, and a parametersetting interface 2130 a. The user interface 2100 a could be presentedby a touchscreen disposed in the flexible exosuit (e.g., in a sleeve ofthe flexible exosuit) or could be presented by some other system incommunication with the flexible exosuit (e.g., a cellphone). The statusvariable display 2110 a indicates user-selectable values to the wearer(e.g., the battery life of the flexible exosuit, the wearer's heart rateas detected by sensors of the flexible exosuit). The informationalschematic 2120 a displays a simplified schematic of the flexibleexosuit. The informational schematic 2120 a can additionally indicateinformation about the suit. For example, whether an element of theflexible exosuit is currently being actuated by the flexible exosuitcould be indicated by a change in color of the element of theinformational schematic 2120 a corresponding to the actuated element.

The parameter setting interface 2130 a provides a mechanism for thewearer to manually set one or more parameters related to the operationof the flexible exosuit. In the example of FIG. 21A, the parametersetting interface 2130 a is displaying a pattern of actuator force 2142a versus gait cycle percent. The parameter setting interface 2130 a isadditionally displaying a slider 2140 a configured to be operated by thewearer to change the magnitude of the actuator force 2142 a. The wearercould drag the slider 2140 a to a level corresponding to a level ofactuator force that is comfortable to the wearer. Additionally oralternatively, the wearer could use the slider 2140 a to select a levelof force according to some other consideration or combination ofconsiderations; for example, the wearer could reduce the level ofactuator force to conserve energy in the battery of the flexibleexosuit.

FIG. 21B illustrates another example of a user interface 2100 b for aflexible exosuit. The user interface 2100 b includes a status variabledisplay 2110 b, an informational schematic 2120 b, and a parametersetting interface 2130 b. The user interface 2100 b could be presentedby a touchscreen disposed in the flexible exosuit (e.g., in a sleeve ofthe flexible exosuit) or could be presented by some other system incommunication with the flexible exosuit (e.g., a cellphone). The statusvariable display 2110 b indicates user-selectable values to the wearer(e.g., the battery life of the flexible exosuit, the wearer's heart rateas detected by sensors of the flexible exosuit). The informationalschematic 2120 b displays a simplified schematic of the flexibleexosuit. The informational schematic 2120 b can additionally indicateinformation about the suit. For example, whether an element of theflexible exosuit is currently being actuated by the flexible exosuitcould be indicated by a change in color of the element of theinformational schematic 2120 b corresponding to the actuated element.

The parameter setting interface 2130 b provides a mechanism for thewearer to manually set one or more parameters related to the operationof the flexible exosuit. In the example of FIG. 21B, the parametersetting interface 2130 b is presenting the wearer with interfaceelements that the wearer could operate to set the extent of operation ofactuators of the flexible exosuit operating across the right and leftankles of the wearer. A first slider 2141 b could be operated by thewearer to set a maximum stroke length of the right ankle actuator (i.e.,to set a maximum amount of dorsiflexion of the right ankle that theright ankle actuator will allow to occur). A second slider 2143 b couldbe operated by the wearer to set a minimum stroke length of the rightankle actuator (i.e., to set a maximum amount of plantarflexion of theright ankle that the right ankle actuator can impose on the right ankle)A third slider 2145 b could be operated by the wearer to set a maximumstroke length of the left ankle actuator (i.e., to set a maximum amountof dorsiflexion of the left ankle that the left ankle actuator willallow to occur). A fourth slider 2147 b could be operated by the wearerto set a minimum stroke length of the left ankle actuator (i.e., to seta maximum amount of plantarflexion of the left ankle that the left ankleactuator can impose on the right ankle) The wearer could drag one ormore of the sliders 2141 b, 643 b, 645 b, 647 b to levels thatcorresponded to ankle actuator operation that is comfortable to thewearer. For example, the wearer could be recovering from an injury totheir right ankle. The wearer could set the second slider 2143 b to alevel lower than the fourth slider 1047 b to reflect the fact that thewearer's right ankle is more sensitive and/or has a smaller range ofmotion than the wearer's left ankle due to the injury.

A parameter setting interface 2130 a, 2130 b could be configured topresent additional or alternate settings, parameters, controls, or otheruser interface elements to the wearer. For example, the parametersetting interface 2130 a, 2130 b could present the user with a varietyof controllers and/or applications that could be executed to operate theflexible exosuit to enable operating modes of the suit, e.g., increasingthe efficiency of locomotion of the wearer, enhancing the strength ofthe wearer, allowing the wearer to jump higher, or other functions.Further, the parameter setting interface 2130 a, 2130 b could provideuser-settable parameters respective to controllers and/or applicationsexecuted by the flexible exosuit. For example, the parameter settinginterface 2130 a, 2130 b could allow the wearer to set a magnitude of aforce applied to the wearer's ankles to assist the wearer to jump. Thewearer could set such a setting according to the distance the wearerintended to jump, the mass of a load carried by the wearer, or someother consideration. Other parameters and configurations of parametersetting interfaces 2130 a, 2130 b are anticipated.

A status variable display 2110 a, 2110 b of a user interface 2100 a,2100 b could indicate additional or alternate information to the heartrate and battery status illustrated in the examples of FIGS. 21A and21B. For example, the metabolic rate of the wearer, the distance awearer has traveled since some waypoint, the distance a wearer has yetto travel to a destination, an operating mode of the flexible exosuits,or some other information could be presented to the wearer by the statusvariable display 2110 a, 2110 b. In some examples, the informationdisplayed by the status variable display 2110 a, 2110 b and otherproperties of the status variable display 2110 a, 2110 b could becontrolled by the wearer. For example, the wearer could choose throughsome element of the user interface (not shown) what information isdisplayed by the status variable display 2110 a, 2110 b. Additionally oralternatively, the information indicated by the status variable display2110 a, 2110 b could be related to the current operation and/or statusof the flexible exosuit, the wearer, and/or the environment of thewearer. For example, if the user has operated the flexible exosuit toassist the user to jump, the status variable display 2110 a, 2110 bcould display a countdown to the time when the flexible exosuit willapply the forces and/or torques necessary to assist the wearer to jump.In some examples, pressing information indicated by the status variabledisplay 2110 a, 2110 b could cause a window or application to be openedrelated to the indicated information that was pressed. For example, if awearer pressed an indication of the wearer's heart rate, a windowillustrating the wearer's ECG and other health and/or physiologicalinformation about the wearer could be displayed. Other informationdisplayed by the status variable display 2110 a, 2110 b and methods ofwearer interaction with the status variable display 2110 a, 2110 b areanticipated.

An informational schematic 2120 a, 2120 b of a user interface 2100 a,2100 b could indicate a variety of information to a wearer about aflexible exosuit and could be configured to operate according to avariety of applications. In some examples, a shape, color, sizeanimation, or other information about elements of the informationalschematic 2120 a, 2120 b could indicate a variety of information aboutcorresponding elements of the flexible exosuit. In some examples, theinformational schematic 2120 a, 2120 b could be operated to indicatethat elements of the flexible exosuit are being used, are in need ofcalibration, are damaged, are in need of replacement, or otherinformation. In some examples, the schematic representing the flexibleexosuit in the informational schematic 2120 a, 2120 b could be animated,and the animation could indicate an operational mode of the flexibleexosuit. Additionally or alternatively, the schematic representing theflexible exosuit could be animated to mirror the motions and/orconfiguration of the flexible exosuit and/or the wearer. In someexamples, the wearer could press elements of the informational schematic2120 a, 2120 b to access more information and/or parameter settings,controls, or applications related to the elements of the informationalschematic 2120 a, 2120 b pressed by the wearer. For example, pressing anelement on the informational schematic 2120 a, 2120 b corresponding toankle actuators could cause the parameter setting interface 2130 b shownin FIG. 21B to be displayed. For example, pressing an element on theinformational schematic 2120 a, 2120 b corresponding to a sensor couldcause an indication of current and/or past measurements made using thesensor to be displayed. Other information displayed by the informationalschematic 2120 a, 2120 b and methods of wearer interaction with theinformational schematic 2120 a, 2120 b are anticipated.

A user interface 2100 a, 2100 b of a flexible exosuit could beconfigured to provide additional information and/or functionality. Insome examples, the user interface 2100 a, 2100 b could enable a weareror some other person or system to log or record one or more measurementsrelated to the flexible exosuit, the wearer, the environment of theflexible exosuit, the interaction between the wearer and the flexibleexosuit, or some other information related to the flexible exosuit. Theuser interface 2100 a, 2100 b could allow the wearer to view therecorded information and/or to perform analyses on the recordedinformation. For example, the wearer could operate the user interface2100 a, 2100 b to record information about the wearer's gait whilerunning, and could use the user interface 2100 a, 2100 b to performanalyses on the wearer's gait to improve the wearer's running technique.The wearer could also use the user interface 2100 a, 2100 b to makerecorded information available to other persons or systems. For example,the wearer could make recorded information available to a teacher,coach, physician, or other individual.

In some examples, a wearer could operate the user interface 2100 a, 2100b to access previously recorded information about the flexible exosuit,the wearer, the environment of the flexible exosuit, and/or theinteraction between the wearer and the flexible exosuit and to use topreviously recorded information to affect the operation of the flexibleexosuit. For example, the accessed data could be used as a baseline ofcomparison to enable the wearer to compare the wearer's currentperformance of a task to the wearer's past performance of the taskrepresented by the accessed data. That is, the wearer could performanalyses to compare the wearer's progress at learning a task and/or todetermine a change in the wearer's physical abilities. In anotherexample, the flexible exosuit could be operated to guide the wearer inre-enacting the activity or motions represented by the accessed data.

In some examples, previously recorded data could be used to updateparameters or other configuration data of applications, controllers,other services, drivers, daemons, or other computer-readable programsused to operate the flexible exosuit. For example, the parameters orother configuration data could be updated to reflect a specific wearer'spattern of walking, and the updated the parameters or otherconfiguration data could be used by the computer-readable programs tochange a timing of actuation of elements of the flexible exosuit to moreaccurately reflect the timing of a user's motion during walking. In someexamples, previously recorded data could be associated with the wearerbecoming fatigued, and the flexible exosuit could be operated to detectthat the wearer is becoming fatigued by detecting that a currentproperty of the actions of the wearer is similar to actions of thewearer represented in the previously recorded data that are associatedwith the wearer becoming fatigued. The operation of the flexible exosuitcould be changed in response to such a determination; for example, themagnitude to which the flexible exosuit operated actuators of theflexible exosuit to assists actions of the wearer could be increasedand/or the flexible exosuit could indicate that the wearer was becomingfatigued to the wearer or to a remote person or system in communicationwith the flexible exosuit. Other applications of previously recordedinformation about the flexible exosuit, the wearer, the environment ofthe flexible exosuit, and/or the interaction between the wearer and theflexible exosuit to operate a flexible exosuit and/or to effect otheroperating modes of the flexible exosuit are anticipated.

In some examples, a wearer could operate the user interface 2100 a, 2100b to provide recorded information about the flexible exosuit, thewearer, the environment of the flexible exosuit, and/or the interactionbetween the wearer and the flexible exosuit and to use to previouslyrecorded information to a remote system (e.g., a server). The remotesystem could receive such recorded information from a plurality ofwearers of flexible exosuit and could generate a reference data set fromthe received recorded information. The remote system could performanalyses or other computations on the reference data set. Results of theperformed analyses or other computations on the reference data set couldbe provided to individual flexible exosuits to improve the operation ofthe individual flexible exosuits (e.g., to update parameters or otherconfiguration data of applications, controllers, other services,drivers, daemons, or other computer-readable programs used to operatethe individual flexible exosuits). For example, the remote server coulddetermine that an individual wearer was performing a task better thanthe performance of the task represented by the current reference dataset, and the remote server could responsively update the reference dataset to reflect the data received from the flexible exosuit worn by theindividual wearer. Other applications and operations of remote systemsin communication with a plurality of flexible exosuits are anticipated.A user interface 2100 a, 2100 b of a flexible exosuit could beconfigured to provide additional information and/or functionality. Insome examples, the user interface 2100 a, 2100 b could present thewearer with a home screen. The home screen could display a variety ofapplications, operating modes, functions, and settings of the flexibleexosuit as icons that the wearer could press. Pressing an icon couldcause an application, program, or other function to be executed. Forexample, pressing a button for a jump application could cause the jumpapplication to begin execution, and the jump application could operateelements of the flexible exosuit to assist the wearer in jumping. Thejump application could additionally present an interface to the wearerthat could include methods for controlling aspects of the jumpapplication, for example, jump timing, jump height, jump power, jumpsymmetry, or other methods of controlling the jump application. The homescreen could additionally provide methods for the wearer to stopapplications that are running, determine whether and which applicationsare running, or other functions. Other applications, methods ofinteracting with and/or presenting a home screen to a wearer, menusaccessible from a home screen or by some other method, methods ofinteraction between an application of a flexible exosuit and a wearer,and other configurations and applications of a user interface 2100 a,2100 b of a flexible exosuit are anticipated.

A user interface 2100 a, 2100 b of a flexible exosuit could additionallyprovide methods for a wearer to browse applications for the flexibleexosuit, purchase exosuit applications, download exosuit applications,install exosuit applications, configure exosuit applications, uninstallexosuit applications, or other functions related to applicationsconfigured to be executed by a flexible exosuit. The user interface 2100a, 2100 b could allow a wearer to access a profile or account related tothe wearer and to the purchasing, installing, updating, andpersonalization of exosuit applications. Other applications, methods ofinteracting with and/or presenting a user interface 2100 a, 2100 b to awearer, methods of interaction between a user interface 2100 a, 2100 bof a flexible exosuit and a wearer, and other configurations andapplications of a user interface 2100 a, 2100 b of a flexible exosuitare anticipated.

CONCLUSION

Embodiments described herein are intended as illustrative, non-limitedexamples of flexible exosuits. Further, elements, actuators, sensors,garments, or other systems and devices described herein in the contextof their use as elements of a flexible exosuit could additionally oralternatively be used to enable other applications. For example,actuators, sensors, and other devices and system described herein couldbe configured for use as part of robots, assistive devices, vehicles,toys, appliances, prosthetics, or other mechatronic systems or devices.

Flexible exosuits as described herein may be configured in a variety ofways according to a variety of applications. A flexible exosuit may beconfigured to apply forces to the lower body, upper body, torso, orcombinations of some or all of these parts of a wearer. A flexibleexosuit could be symmetric (able to apply the same types of forces andtorques to one side of a wearer's body as to the opposite side) or couldbe asymmetric (e.g., to enable strength assists and/or rehabilitation toa wearer that has experienced an injury to one limb and not to theopposite limb). Different overall topologies of configuration offlexible exosuits may correspond to and/or be specified by respectiveapplications of flexible exosuits.

Dimensions, configurations, sets of actuators, or other properties of aflexible exosuits as described herein could be configured to be used bya variety of users (e.g., a one-size-fits-all device, a device includingstraps, buttons, fasteners, or other means to adjust a dimension orother property to a wearer) or could be custom-tailored or otherwisemanufactured specifically for an individual user. Some elements of aflexible exosuit (e.g., TSAs, user interfaces) could have a single sizeand/or configuration for a variety of users, while other elements (e.g.,undersuits, rigid force-transmitting elements, flexibleforce-transmitting elements) could be chosen from sets of elementshaving a range of sizes such that the chosen elements had a size matchedto the wearer. 3D printing, rapid prototyping, or other methods ofcustomized fabrication could be used to produce elements of a flexibleexosuit specifically configured to be worn and/or used by a specificwearer.

Flexible exosuits as described herein could be operated according to avariety of applications. Applications of a flexible exosuit as describedherein are not limited to the functions or operating modes enumeratedherein, and could include other applications enabled by the use of areconfigurable system configured to apply forces and/or torques to abody of a wearer. Applications could include but are not limited torehabilitation, augmentation, training, entertainment, immersive virtualreality, exercise, and communications.

Flexible exosuits as described herein could be configured for use byanatomically typical human wearers or by atypical human wearers.Flexible exosuits could be configured to be worn and operated by humanwearers that have lost parts of their body (e.g., arms, legs), that haveexperienced some alteration of anatomy due to surgical intervention(e.g., tendon transfer) or that are anatomically atypical. Configurationof flexible exosuits for use and/or operation by human wearers asdescribed above could include hardware configuration (e.g., omittingelements of a standard exosuit that correspond to a missing limb of awearer) and/or software configuration (e.g., altering a controller orother computer-readable program of the flexible exosuit to take intoaccount that a wearer is unable to activate his/her triceps muscles dueto tetraplegia).

Flexible exosuits as described herein could be configured for use bynon-human animals. For example, a flexible exosuit could be configuredto be worn by a non-human primate, a dog, a horse, or some other animalaccording to an application, e.g., animal training.

The particular arrangements shown in the Figures should not be viewed aslimiting. It should be understood that other embodiments may includemore or less of each element shown in a given Figure. Further, some ofthe illustrated elements may be combined or omitted. Yet further, anexemplary embodiment may include elements that are not illustrated inthe Figures.

Additionally, while various aspects and embodiments have been disclosedherein, other aspects and embodiments will be apparent to those skilledin the art. The various aspects and embodiments disclosed herein are forpurposes of illustration and are not intended to be limiting, with thetrue scope and spirit being indicated by the following claims. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which arecontemplated herein.

What is claimed is:
 1. A programmable body augmentation system,comprising: a flexible suit configured to be worn over at least aportion of a human body; one or more flexible linear actuators coupledto the flexible suit, wherein the one or more flexible linear actuatorsare operable to apply forces between segments of the human body suchthat the forces applied by the one or more flexible linear actuatorsaugment forces applied by musculature in the human body; one or moreclutched-compliance elements coupled to the flexible suit, wherein theone or more clutched-compliance elements are operable to providecontrollable levels of compliance between segments of the human body;and a controller disposed in the flexible suit, wherein the controlleris configured to execute computer-readable programs to operate the oneor more flexible linear actuators to apply forces between segments ofthe human body and to operate the clutched-compliance elements toprovide controlled levels of compliance between segments of the humanbody in a plurality of different ways to provide a plurality ofdifferent modes of operation.
 2. The programmable body augmentationsystem of claim 1, wherein the plurality of different modes of operationrelate to one or more of walking, running, jumping, lifting, loadcarrying, climbing, cycling, exercising, training, controlling a virtualavatar, and controlling a tele-robotic system.
 3. The programmable bodyaugmentation system of claim 1, wherein the plurality of different modesof operation relate to different potential wearers of the programmablebody augmentation system.
 4. The programmable body augmentation systemof claim 1, wherein the controller can execute any of a plurality ofstored computer-readable programs, wherein execution of a storedcomputer-readable program by the controller comprises operating the oneor more flexible linear actuators and the one or moreclutched-compliance elements in accordance with the storedcomputer-readable program, and wherein each of the storedcomputer-readable programs defines at least one of the plurality ofdifferent modes of operation.
 5. The programmable body augmentationsystem of claim 4, wherein operating the one or more flexible linearactuators in accordance with the stored computer-readable programcomprises controlling the timing and magnitude of forces applied by eachof the flexible linear actuators.
 6. The programmable body augmentationsystem of claim 4, wherein operating the one or more clutched-complianceelements in accordance with the stored computer-readable programcomprises controlling a level of compliance provided by each of the oneor more clutched-compliance elements.
 7. The programmable bodyaugmentation system of claim 4, further comprising one or more kinematicsensors configured to provide data to the controller, wherein operatingthe one or more flexible linear actuators and the one or moreclutched-compliance elements in accordance with the storedcomputer-readable program comprises operating the one or more flexiblelinear actuators and the one or more clutched-compliance elements inresponse to the data provided by the one or more kinematic sensors. 8.The programmable body augmentation system of claim 4, further comprisinga user interface, wherein the user interface is operable to select anyof the plurality of stored computer-readable programs for execution bythe controller.
 9. The programmable body augmentation system of claim 8,wherein the user interface is operable to select additionalcomputer-readable programs that define additional modes of operation ofthe programmable body augmentation system.
 10. The programmable bodyaugmentation system of claim 1, wherein the one or more flexible linearactuators are configured to apply forces across one or more joints,wherein the one or more joints include at least one of an ankle joint, aknee joint, or a hip joint.
 11. The programmable body augmentationsystem of claim 1, wherein the one or more clutched-compliance elementsare configured to provide a controllable compliance across one or morejoints, wherein the one or more joints include at least one of an anklejoint, a knee joint, or a hip joint.
 12. The programmable bodyaugmentation system of claim 1, wherein at least one of the one or moreflexible linear actuators comprises a twisted string actuator.
 13. Theprogrammable body augmentation system of claim 12, wherein the twistedstring actuator comprises an electric motor coupled to a string elementcomprising a plurality of flexible strands.
 14. The programmable bodyaugmentation system of claim 1, wherein each of the clutched-complianceelements includes a respective electrostatic clutch.
 15. Theprogrammable body augmentation system of claim 14, wherein at least oneof the respective electrostatic clutches comprises an electrolaminateclutch.
 16. The programmable body augmentation system of claim 1,wherein the one or more clutched-compliance elements include at leastone clutched-compliance element connected in series with a flexiblelinear actuator.